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Secondary and High School students are usually adolescents, most of them in the urban areas and metropolitan cities are aware about the existence, various opportunities, career paths and advancements of the space industry. They are constantly updated, given they have access to quality and organized education models and a competitive environment. Although, the students in the rural areas who are equally ambitious and talented yet are not fortunate enough to have access to the state of art facilities like the counterparts. Even if they try and gain access with their self-interest, they do not have the motivation to sustain the passion, given their lack of clarity in subject, lack of awareness about engaging in various ways and fields in space other than technological related and mainly lack of driving force. The purpose of this paper is to develop and present an education model, exclusively for the high school students of the rural areas and inculcate sustainable passion for space. As opposed to the primary school students, the secondary school students have a consciousness of the space industry. This paper will talk about various plans and strategies, that will allow them to gain exposure, guide them about the existence of different career paths which are not entirely technological related, yet are still essential in the space like, administrative framework for example. This opens a new dimension in their brain helping them realize how they can be part of the industry in countless ways, and this shall assist them in being on the right track to space. In addition to, hosting creative space themed exhibitions, fun and engaging model design competitions, workshops, all of these would widen their knowledge boundaries and help them challenge their skills. A real time case study example from a school located in the rural southern of India shall be focused on this paper. Including data from a survey thereby the results, with action plans shall be presented in detail, which will aid in the analysis of the need, feasibility, and long-term sustenance of this approach and the requirement to scale it over different rural areas globally. • Need for improvised education models in rural areas elucidated, with data collection. • Data analysis and correlation of space education awareness, for high school students across two geographical locations. • Readily executable action plans age groupwise, for real-time education models in remote areas globally. [ABSTRACT FROM AUTHOR]

Artificial Intelligence (AI) has transformed the way human-computer interaction (HCI) teams are able to collaborate and coordinate in various domains, including aviation. AI's transformative capabilities can enhance teamwork, efficiency, and safety, particularly in risk management. AI's ability to process vast amounts of data and provide real-time insights enables informed decision-making and automation of repetitive tasks in aviation. By combining the strengths of AI and humans, outlined in our modified version of the 'HABA-MABA' framework, a dynamic teamwork relationship emerges, provided roles are successfully allocated. AI systems are able to act as intelligent assistants, offering timely recommendations, fostering effective communication, and facilitating coordination among crew members. Its adaptability and capacity for learning improve collaboration abilities, tailoring strategies to meet the team's specific needs. This paper explores the theories, considerations, and implications of human-AI teams in aviation, highlighting potential benefits, training recommendations, and future research directions. While human-AI teams offer numerous benefits, addressing the risks, limitations, and ethical considerations is crucial to ensuring safe and efficient operations. Future research must prioritize transparency, explainability, adaptability, and real-world testing to unlock the full potential of human-AI teams and foster successful integration across diverse domains. [ABSTRACT FROM AUTHOR]

The paper presents a wireless system integrated with a machine learning (ML) model for structural health monitoring (SHM) of carbon fiber reinforced polymer (CFRP) structures, primarily targeting aerospace applications. The system collects data via carbon nanotube (CNT) piezoresistive sensors embedded within CFRP coupons, wirelessly transmitting these data to a central server for processing. A deep neural network (DNN) model predicts mechanical properties and can be extended to forecast structural failures, facilitating proactive maintenance and enhancing safety. The modular design supports scalability and can be embedded within digital twin frameworks, offering significant benefits to aircraft operators and manufacturers. The system utilizes an ML model with a mean absolute error (MAE) of 0.14 on test data for forecasting mechanical properties. Data transmission latency throughout the entire system is less than one second in a LAN setup, highlighting its potential for realtime monitoring applications in aerospace and other industries. However, while the system shows promise, challenges such as sensor reliability under extreme environmental conditions and the need for advanced ML models to handle diverse data streams have been identified as areas for future research. [ABSTRACT FROM AUTHOR]

Hall thrusters are electric propulsion devices that are widely used in modern spaceflight. To obtain the critical corrosion data effectively and accurately during long-life tests of Hall thrusters, this paper proposes an automated corrosion measurement method based on three-dimensional point cloud technology. This method uses binocular structured light scanning method to obtain surface point cloud data. The point cloud topology relationship of these disordered data is also established by KD-tree and radius filtering. The base plane is determined according to the average of the outer circle plane in the discharge chamber, and the original point cloud data is sliced transversely and longitudinally. The point cloud of section data is extracted and the corrosion width data is obtained according to the round hole feature extraction and center of circle calculation. The corrosion angle is calculated according to the angle between the straight line and the normal of the section. The proposed method has been verified and the results show that the overall error accuracy is within 60 μm, which meets the requirements for automatic measurement of Hall thruster corrosion. It is a real and effective method to obtain the critical corrosion data during long-life tests of Hall thrusters. [ABSTRACT FROM AUTHOR]

This paper presents the findings of detailed and comprehensive technical literature aimed at identifying the current and future research challenges of tactical autonomy. It discusses in great detail the current state-of-the-art powerful artificial intelligence (AI), machine learning (ML), and robot technologies, and their potential for developing safe and robust autonomous systems in the context of future military and defense applications. Additionally, we discuss some of the technical and operational critical challenges that arise when attempting to practically build fully autonomous systems for advanced military and defense applications. Our paper provides the state-of-the-art advanced AI methods available for tactical autonomy. To the best of our knowledge, this is the first work that addresses the important current trends, strategies, critical challenges, tactical complexities, and future research directions of tactical autonomy. We believe this work will greatly interest researchers and scientists from academia and the industry working in the field of robotics and the autonomous systems community. We hope this work encourages researchers across multiple disciplines of AI to explore the broader tactical autonomy domain. We also hope that our work serves as an essential step toward designing advanced AI and ML models with practical implications for real-world military and defense settings. [ABSTRACT FROM AUTHOR]

3-dimensional (3D) flux machines accommodate many design and analysis challenges. Transverse flux machines (TFMs) are mostly useful for low speed, high torque applications but in this research a fault tolerant transverse flux alternator with segmented stator has been prototyped and several important design and manufacturing challenges have been thoroughly investigated as different scenarios. The proposed machine consists of axially separated, 4-single phase to achieve low speed power of 40 Watts at 400 revolutions/minute (rpm). In addition, the machine must achieve several high-speed specifications at 15,000 rpm. It is demonstrated that the proposed TFM could be an alternative to more conventional radial flux machines in aerospace as validated within the paper. However, the necessity of stator segmentation and the use of soft magnetic composites for the proposed 3D flux machine lead to many important design and optimization considerations. Therefore, this paper investigates the manufacturing and material uncertainties in a TFM for an aerospace application. The results indicate that transverse flux alternator might be an option as an aerospace alternator but the peak performance of the prototype machine is still far from the 3D models investigated using finite element electromagnetic simulations. [ABSTRACT FROM AUTHOR]

In aerospace applications, SiOx deposition on perovskite solar cells makes them more stable. However, the reflectance of the light changes and the current density decreases can lower the efficiency of the solar cell. The thickness of the perovskite material, ETL, and HTL must be re-optimized, and testing the number of cases experimentally takes a long time and costs a lot of money. In this paper, an OPAL2 simulation was used to find the thickness and material of ETL and HTL that reduces the amount of light reflected by the perovskite material in a perovskite solar cell with a silicon oxide film. In our simulations, we used an air/SiO2/AZO/transport layer/perovskite structure to find the ratio of incident light to the current density generated by the perovskite material and the thickness of the transport layer to maximize the current density. The results showed that when 7 nm of ZnS material was used for CH3NH3PbI3-nanocrystalline perovskite material, a high ratio of 95.3% was achieved. In the case of CsFAPbIBr with a band gap of 1.70 eV, a high ratio of 94.89% was shown when ZnS was used. [ABSTRACT FROM AUTHOR]

The article reviews the development, current use, and future potential of magnesium alloys in the aerospace industry. Magnesium alloys are valued for their high specific strength, stiffness, excellent damping properties, electromagnetic shielding, and thermal conductivity. These properties make them particularly useful for manufacturing critical components in aircraft, missiles, and spacecraft, as they reduce weight and enhance performance. China is a leading producer of magnesium alloys, with substantial use in aerospace, contributing to lighter aircraft and spacecraft, improved maneuverability, and lower launch costs. Despite their advantages, magnesium alloys face challenges, including poor corrosion resistance, low strength at high temperatures, and casting difficulties. The paper discusses the evolution of magnesium alloys, noting their early use in the 20th century and a resurgence in the 1990s. It highlights ongoing research to develop magnesium-rare earth (Mg-RE) alloys, which offer better strength and high-temperature resistance. The paper also outlines the limitations of magnesium alloys compared to aluminum alloys, which remain dominant due to superior overall performance. In the future, advancements in surface treatments, manufacturing processes, and alloy compositions are crucial for overcoming current limitations, enabling broader use of magnesium alloys in aerospace applications. [ABSTRACT FROM AUTHOR]

The scientific community is and has constantly been working to innovate and improve the available technologies in our use. In that effort, three-dimensional (3D) printing was developed that can construct 3D objects from a digital file. Three-dimensional printing, also known as additive manufacturing (AM), has seen tremendous growth over the last three decades, and in the last five years, its application has widened significantly. Three-dimensional printing technology has the potential to fill the gaps left by the limitations of the current manufacturing technologies, and it has further become exciting with the addition of a time dimension giving rise to the concept of four-dimensional (4D) printing, which essentially means that the structures created by 4D printing undergo a transformation over time under the influence of internal or external stimuli. The created objects are able to adapt to changing environmental variables such as moisture, temperature, light, pH value, etc. Since their introduction, 3D and 4D printing technologies have extensively been used in the healthcare, aerospace, construction, and fashion industries. Although 3D printing has a highly promising future, there are still a number of challenges that must be solved before the technology can advance. In this paper, we reviewed the recent advances in 3D and 4D printing technologies, the available and potential materials for use, and their current and potential future applications. The current and potential role of 3D printing in the imperative fight against COVID-19 is also discussed. Moreover, the major challenges and developments in overcoming those challenges are addressed. This document provides a cutting-edge review of the materials, applications, and challenges in 3D and 4D printing technologies. [ABSTRACT FROM AUTHOR]

This paper presents the study of power/ground (P/G) supply-induced jitter (PGSIJ) on a cascaded inverter output buffer. The PGSIJ analysis covers the IO buffer transient simulation under P/G supply voltage variation at three process, voltage, and temperature (PVT) corners defined at different working temperatures and distinct P / G DC supply voltages at the pre-driver (i.e., V D D / V S S ) and last stage (i.e., V D D Q / V S S Q ). Firstly, the induced jitter contributions by the pre-driver, as well as the last, stage are compared and studied. Secondly, the shared and decoupled P/G supply topologies are investigated. The outcomes of these simulation analyses with respect to worst case jitter corners are determined, while highlighting the importance of modeling the pre-driver circuit behavior to include the induced jitter in the input–output buffer information specification (IBIS)-like model. Accordingly, the measured PGSIJ depends on the corners to be analyzed and, therefore, the designer needs to explore the worst-case corner for the driver's technology node and the most supply voltage noise affecting the jitter output for signal and power integrity (SiPI) simulations. Finally, the jitter transfer function sensitivity to the amplitude and frequency/phase variations of the separate and combined impacts of the pre-driver and last stage are explored, while discussing the superposition of the power supply induced jitter (PSIJ) induced by both the driver's IO stages under small signal and large signal supply voltage variations. The linear superposition of the separate PSIJ effects by the pre-driver and last stage depends on the amplitude of the variation of the supply voltage that can drive the transistor to their nonlinear working regions. [ABSTRACT FROM AUTHOR]

Autoclave is the technology that has been extensively used to manufacture high-grade performance composite parts for aerospace applications. This technology has been limited to aerospace industries only, primarily due to its high cost in manufacturing parts. The researchers then considered an alternative approach "Out-of-autoclave" (OOA) process, aiming at cost and time optimization. Nonautoclave methods such as OOA cure processes have been developed lately. The OOA process has a high potential for a drastic cost reduction in the manufacturing of composite aerospace structures. It processes parts that have a quality similar to that of parts cured using the autoclave technology. Specially designed OOA prepregs are available in the market for OOA processing, some of which are certified for aerospace manufacturing. This review paper briefly focuses on OOA prepregs and OOA processes that are used for aerospace components manufacturing. Future areas of development in the aerospace sector based on cost optimization and faster cycle times are also discussed in this paper. [ABSTRACT FROM AUTHOR]

In this study, the development of innovative tooling and end-effector systems for the assembly of a multifunctional thermoplastic fuselage is presented. The increasing demand for cleaner and new aircraft requires utilising novel materials and technologies. Advanced thermoplastic composites provide an excellent material option thanks to their weldability, low density, low overall production cost, improved fracture toughness and recyclability. However, to fully appreciate their potentials, new manufacturing approaches and techniques are needed. Hence, this project develops three end-effector solutions to demonstrate the feasibility of assembling a full-scale multifunctional-integrated thermoplastic lower fuselage shell, including the integration of a fully equipped floor and cargo structure. The developed assembly solution comprises three individual yet well-integrated tooling systems that allow housing the skin and assembly; picking, placing and welding of the assembly parts, i.e. clips and stringers; and welding of frames and floor beam sub-assemblies. The process of developing these systems including the end-user requirements, technical challenges, tooling and end-effectors design and manufacturing process are detailed in this paper. [ABSTRACT FROM AUTHOR]

A solar sail based on the physics of diffracted light provides a means of harnessing opto-mechanical momentum for in-space propulsion. As an example a heuristic roll maneuver of a diffractive sail is found to produce a spiral trajectory that provides a high orbital inclination angle at a close solar orbit. A comparison of five-year spiral trajectories of ideal diffractive and reflective sails reveals that the former achieves a higher solar inclination angle and a smaller orbital radius than the latter. We envision placing a constellation of diffractive solar sails around the sun to collect images and other data for space weather monitoring and heliophysics science. For illustration purposes we consider a series of 14 [kg], 400 [m 2 ] lightsails at various inclination angles, all positioned at 0.32 [AU] within six years. This paper may inspire materials scientists to design and fabricate thin novel optical metamaterial films that efficiently diffract light at large angles across the solar spectrum for future solar sails. Mission designers may also be prompted to imagine alternatives beyond reflective sails. • Solar sails are advantageous for inclination cranking of solar polar orbiters. • Diffractive solar sails may prove to be more effective than reflective solar sails. • Diffractive sails enable the placement of a constellation of solar instruments. [ABSTRACT FROM AUTHOR]

Drilling using quasi-continuous wave (QCW) millisecond pulse fibre laser is the state-of-the-art for producing film-cooling holes over uncoated aero-engine components. Laser drilling of coated components, including thermal barrier coated (TBC) components, is still a challenging task due to the risk of coating delamination. Water-jet guided (WJG) laser is nowadays increasingly used for machining of advanced materials such as ceramics and composites. This paper aims to study the basic fundamental characteristics of WJG lasers drilling of acute angular holes over TBC coated nickel superalloy and compare it with the state-of-the-art QCW millisecond fibre laser. Experiments were performed to investigate the characteristics of both QCW and WJG laser drilling in terms of TBC delamination, recast layer formation, hole surface topology and cycle time. Finite element analysis based numerical model was developed and used, to understand and confirm the mechanism of heat propagation and the subsequent material removal characteristics for both WJG and QCW laser. Experimental results show that the WJG laser drilling quality (in terms of thermal damages) is very similar to the process of cold-ablation (i.e. machining without inducing any thermal defects within the substrate material). The numerical model confirms the hypothesis that the high-temperature zone of WJG laser machining process is wholly confined within the small laser irradiation zone, which helps to avoid the TBC delamination typically observed with long pulse acute angle laser drilling process. The material removal mechanism of WJG laser machining seems to be the combination of melt ejection by vapour pressure, melt ejection by impulse shock pressure and by the action of water-jet pressure. [ABSTRACT FROM AUTHOR]

Freedom of design, mass customisation, waste minimisation and the ability to manufacture complex structures, as well as fast prototyping, are the main benefits of additive manufacturing (AM) or 3D printing. A comprehensive review of the main 3D printing methods, materials and their development in trending applications was carried out. In particular, the revolutionary applications of AM in biomedical, aerospace, buildings and protective structures were discussed. The current state of materials development, including metal alloys, polymer composites, ceramics and concrete, was presented. In addition, this paper discussed the main processing challenges with void formation, anisotropic behaviour, the limitation of computer design and layer-by-layer appearance. Overall, this paper gives an overview of 3D printing, including a survey on its benefits and drawbacks as a benchmark for future research and development. [ABSTRACT FROM AUTHOR]

This paper presents the state-of-the-art and reviews the state-of-research of acoustic sensors used for a variety of navigation and guidance applications on air and surface vehicles. In particular, this paper focuses on echolocation, which is widely utilized in nature by certain mammals (e.g., cetaceans and bats). Although acoustic sensors have been extensively adopted in various engineering applications, their use in navigation and guidance systems is yet to be fully exploited. This technology has clear potential for applications in air and surface navigation/guidance for intelligent transport systems (ITS), especially considering air and surface operations indoors and in other environments where satellite positioning is not available. Propagation of sound in the atmosphere is discussed in detail, with all potential attenuation sources taken into account. The errors introduced in echolocation measurements due to Doppler, multipath and atmospheric effects are discussed, and an uncertainty analysis method is presented for ranging error budget prediction in acoustic navigation applications. Considering the design challenges associated with monostatic and multi-static sensor implementations and looking at the performance predictions for different possible configurations, acoustic sensors show clear promises in navigation, proximity sensing, as well as obstacle detection and tracking. The integration of acoustic sensors in multi-sensor navigation systems is also considered towards the end of the paper and a low Size, Weight and Power, and Cost (SWaP-C) sensor integration architecture is presented for possible introduction in air and surface navigation systems. [ABSTRACT FROM AUTHOR]

A sustainable power supply for a wide range of applications, such as powering sensors for structural health monitoring and wireless sensoring nodes for data transmission and communication used in unmanned air vehicles, automobiles, renewable energy sectors, and smart city technologies, is targeted. This paper presents an experimental and numerical study that describes an innovative technique to harvest energy resulted from environmental vibrations. A piezoelectric energy harvester was integrated onto a carbon fibre reinforced polymer (CFRP) laminate structure using the co-curing method. The integrated composite with the energy harvester was lightweight, flexible and provided robust and reliable energy outcomes, which can be used to power different low-powered wireless sensing nodes. A normalised power density of 97 μW cm−3m−2s4 was obtained from resonance frequency of 46 Hz sinusoidal waves at amplitude of 0.2 g; while the representative environmental vibration waves in various applications (aerospace, automotive, machine and bridge infrastructure) were experimentally and numerically investigated to find out the energy that can be harvested by such a multifunctional composite structure. The results showed the energy harvested at different vibration input from various industrial sectors could be sufficient to power an autonomous structural health monitoring system and wireless communications by the designed composite structure. [ABSTRACT FROM AUTHOR]

In this paper, it is shown how to obtain a low-cost, high-resolution, and fault-robust position sensing system for permanent-magnet synchronous motor drives operating in safety-critical systems, by combining binary Hall-effect sensors with high-frequency signal injection. It is shown that the position error signal obtained via signal injection can be merged easily into the quantization-harmonic-decoupling vector-tracking observer that is used to process the Hall-effect sensor signals. The resulting algorithm provides accurate, high-resolution estimates of speed and position throughout the entire speed range; compared to the state-of-the-art drives using Hall-effect sensors alone, the low-speed performance is greatly improved in healthy conditions and also following position sensor faults. It is envisaged that such a sensing system can be successfully used in applications requiring IEC 61508 SIL 3 or ISO 26262 ASIL D compliance, due to its extremely high mean time to failure and to the very fast recovery of the drive following Hall-effect sensor faults at low speeds. Extensive simulation and experimental results are provided on a 3.7-kW interior permanent-magnet drive. [ABSTRACT FROM AUTHOR]

In this paper, binary Hall-effect sensor faults are investigated in rectangular-current-fed brushless dc (BLDC) drives and a very effective methodology for their detection, identification, and compensation is explored. It is shown that these faults cause erroneous commutation, generally leading to unstable operation. Using a fault detection and identification technique proposed by the authors in a recent paper on low-cost field-oriented drives, it is possible to pinpoint the faulty sensors. In this paper, it is demonstrated that the destabilizing effect of these faults on motion-state estimation can be compensated for in any position and speed estimation algorithm, as long as it is properly readapted. To this end, it is shown how to incorporate such fault-compensation in three state-of-the-art estimation algorithms: 1) the zeroth-order algorithm (ZOA); 2) the hybrid observer (HO); and 3) the vector-tracking observer (VTO). Comparative experimental tests are performed and it is verified that stable operation is achieved with three, two, or only a single Hall-effect sensor functioning correctly. These results show that the classical BLDC drive with three Hall-effect sensors has an inherent double redundancy to position-sensor faults. With the proposed method, this property can be exploited in systems that require very high reliability, such as in aerospace and automotive applications. Redundancy can be increased, using more than three Hall-effect sensors; reduced using two sensors; or eliminated using a single sensor, in ultra low-cost applications where redundancy is not a requirement. [ABSTRACT FROM AUTHOR]

In spite of the growing awareness and significance of accounting for sustainability aspects in product development, design decision support is still immature in this end compared to other decision support areas, such as product performance and manufacturability. This paper proposes a novel decision support method that combines qualitative sustainability assessment techniques with a quantitative analysis, without losing transparency and still covering a full sustainability perspective. The aim is to contribute to an understanding for how to enable value assessment of sustainability issues already in early product development situations. The method, named Sustainability Assessment and Value Evaluation, combines two qualitative sustainability assessment techniques with a quantitative Net Present Value analysis based on alternative future scenarios. A case study, related to the development of a new high-temperature aero-engine component, illustrates both how the sustainability assessment identifies hotspots and clarifies potential sustainability consequences for a new product technology, and how Net Present Value is used to assess alternative solution strategies based on the hotspot, to facilitate early stage decision-making in design. The paper argues that the method serves two main purposes: i) to make sustainability consequences more concrete and understandable during design concept selection activities, rather than to have an exact measurement, and ii) to simplify and prioritize, systematically asking what is important in the sustainability analysis, rather than to reduce the sustainability problem. The method allows undertaking the sustainability assessment in a more structured way than what happens today in preliminary design, through scenario building based on socio-ecological assessments, including back-casting to cover the longer time perspective. In addition, the Sustainability Assessment and Value Evaluation-method provided the design team of a means for displaying sustainability consequences on an equal basis with other decision support tool results. [ABSTRACT FROM AUTHOR]

Repairing technologies enable a huge economical potential, especially in high-technology sectors like the aerospace industry with complex capital goods. Companies in these industries retain their knowledge concerning repair technologies, in order to maintain the advantage over their competitors. Thus, the quantity of publications dealing with technological challenges and scientific basics for repairing are limited. The main purpose of this literature review is to collect published information on common technologies regarding the regeneration of turbine blades to extract scientific basics and to present challenges that are currently unattended. The attention of this paper is focused particularly on the machining process. Due to the variety of damages on engine blades, the general process chain has to be adapted partly or in whole for each component. In the second part of this paper, a general process chain for regeneration is presented, including a classification of repair methods. The main interest of the third part addresses the recontouring, which is the final shape cutting of repaired engine blades. At this point, the previous research and occurring challenges are pointed out in two stages related to the machining process-before and during machining. In the last part, the achievable workpiece quality after machining is discussed. [ABSTRACT FROM AUTHOR]

Purpose – This paper aims at investigating the multifaceted nature of innovation networks by focusing on two research questions: Do cluster actors exchange only one type of innovation-related knowledge? Do cluster actors play different roles in innovation-related knowledge exchange? Design/methodology/approach – This paper builds on data collected at the firm level in an Italian aerospace cluster, that is a technology-intensive industry where innovation is at the base of local competitiveness. A questionnaire was used to collect both attribute data and relational data concerning collaboration and the flows of knowledge in innovation networks. The authors distinguished among three types of knowledge (technological, managerial and market knowledge) and five types of brokerage roles (coordinator, gatekeeper, liaison, representative and consultant). Data analysis relied on social network analysis techniques and software. Findings – Concerning the first research question, the findings show that different types of knowledge flow in different ways in innovation networks. The different types of knowledge are unevenly exchanged. The exchange of technological knowledge is open to everyone in the cluster. The exchange of market and managerial knowledge is selective. Concerning the second research question, the authors suggest that different types of cluster actors (large firms, small- and medium-sized enterprises, research centers and universities and institutions for collaboration) do play different roles in innovation networks, especially with reference to the three types of knowledge considered in this study. Research limitations/implications – The present paper has some limitations. First of all, the analysis focuses on just one cluster (one industry in one specific location), cross- and comparative analyses with other clusters may illuminate the findings better, eliminating industry and geographical biases. Second, the paper focuses only on innovation-related knowledge exchanges within the cluster and not across it. Practical implications – The results have practical implications both for policy makers and for managers. First, this research stresses how innovation often originates from a combination of different knowledge types acquired through the collaboration with heterogeneous cluster actors. Further, the analysis of brokerage roles in innovation-driven collaborations may help policy makers in designing programs for knowledge-transfer partnerships among the various actors of a cluster. Social implications – The paper suggests a clear need of developing professional figures capable of operating at the interface of different knowledge domains. Originality/value – The data illuminate several aspects of how innovation takes place in a cluster opening up intriguing aspects that have been overlooked by extant literature. The authors believe that this may trigger several lines of further research on the topic. [ABSTRACT FROM AUTHOR]

More electric is a platform being widely adopted by the current generation of aircraft. It offers significant benefits in terms of fuel savings and flexibility of airframe design but relies on the development of torque dense machines. This paper documents the development of an air-cooled transverse flux machine for use in short-haul aircraft to improve on-ground operational efficiency. If its potential is to be realized, this topology of the machine comes with a new set of manufacturing challenges. Two competing machine layouts with different approaches toward their fabrication are discussed. Experimental results and experiences gained from overcoming the challenges of building the machines are presented. A combined phase topology with soft magnetic composite core-back is shown to give a better rated torque, whereas a separate phase bent lamination concept gives better overload capability. [ABSTRACT FROM AUTHOR]

O-rings are designed to be seated in a groove and compressed during assembly between two or more parts, creating a seal at the interface. The joint may be static, or (in a few circumstances) may have relative motion between parts and O-ring (rotating pump shafts and hydraulic cylinders, for example). Starting from the functionality of O-rings, the component materials can be described. Synthetic rubber, EPDM (ethylene-propylene diene monomer) is one of the most popular, versatile and long-lasting elastomeric material that is suitable for a wide range of applications, such as those in the aerospace domain, presenting a good behavior in extreme temperatures and high ozone resistance. The paper presents an experimental study using EPDM - Nordel 4760, butylic rubber (IIR)- Butyl 268 and clorobutylic rubber (Cl-IIR) - Chlorobutyl HT 1066 and a nanometric agent. As the targeted application of these materials is a specific one for extreme temperatures conditions, a testing matrix was developed, aimed to qualify their technical performance. The mechanical resistance of elastomers recommends the quality of its nanomodified version through superior performance. The structure of the analyzed materials proved to be unaltered when subjected to low temperatures, exhibiting good mechanical performance suitable for the targeted application. [ABSTRACT FROM AUTHOR]

This paper develops an \mathcalL_1 adaptive output feedback controller for a class of underactuated multi-input multi-output (MIMO) systems. The proposed approach is applied as an augmentation of an existing three-loop autopilot. The adaptive scheme is introduced to compensate for the uncertainties and to recover the nominal performance. Stability and performance, both in transient and steady state, are analyzed. Nonlinear simulation results demonstrate the performance of the augmented control system. [ABSTRACT FROM AUTHOR]

In this paper, a permanent magnet alternator which presently relies on magnetic slot wedges is redesigned to give lower iron loss. The new segmented stator design is used as the basis for a validated loss study—comparing bonded lamination stacks with those held together with a punched notch. Segmentation is shown to improve the production process, reduce losses, and remove the need for wedges, while not significantly altering the acoustic performance. In the first series of prototypes, however, where notching is used to secure lamination packs, the process is shown to have adversely affected material properties of the nickel iron laminations and overall measured losses increased. In the second prototype, with thinner laminations and glued stacks, iron loss predictions and measurement agree and are less than the present slot wedge design. [ABSTRACT FROM AUTHOR]

In real aircraft structures the comfort and the occupational performance of crewmembers and passengers are affected by the presence of noise. In this sense, special attention is focused on mechanical and material design for isolation and vibration control. Experimental characterization and, in particular, experimental modal analysis, provides information for adequate cabin noise control. Traditional sensors employed in the aircraft industry for this purpose are invasive and provide a low spatial resolution. This paper presents a methodology for experimental modal characterization of a front fuselage full-scale demonstrator using high-speed 3D digital image correlation, which is non-invasive, ensuring that the structural response is unperturbed by the instrumentation mass. Specifically, full-field measurements on the passenger window area were conducted when the structure was excited using an electrodynamic shaker. The spectral analysis of the measured time-domain displacements made it possible to identify natural frequencies and full-field operational deflection shapes. Changes in the modal parameters due to cabin pressurization and the behavior of different local structural modifications were assessed using this methodology. The proposed full-field methodology allowed the characterization of relevant dynamic response patterns, complementing the capabilities provided by accelerometers. [ABSTRACT FROM AUTHOR]

This paper presents the evaluation process and results associated with two different fault detection and diagnosis (FDD) schemes applied to two different aircraft actuator fault benchmark problems. Although the schemes are different and bespoke for the problem being addressed, both are based on the concept of a second order sliding mode. Furthermore both designs are considered as 'local' in the sense that a localized actuator model is used together with local sensor measurements. The schemes do not involve the global aircraft equations of motion, and therefore have low order. The first FDD scheme is associated with the detection of oscillatory failure cases (OFC), while the second scheme is aimed at the detection of actuator jams/runaways. For the OFC benchmark problem, the idea is to estimate the OFC using a mathematical model of the actuator in which the rod speed is estimated using an adaptive second order exact differentiator. For the jam/runaway actuator benchmark problem, a more classical sliding mode observer based FDD scheme is considered in which the fault reconstruction is obtained from the equivalent output error injection signals associated with a second order sliding mode structure. The results presented in this paper summarize the design process from tuning, testing and finally industrial evaluation as part of the ADDSAFE project. [ABSTRACT FROM AUTHOR]

National governments are keenly aware of the need for investment in space. Canada, as a formal cooperating state in the European Space Agency (ESA), and Germany, as a leading member state of ESA, are interlinked in Europe's space endeavours. Beyond ESA, Germany and Canada additionally have a strong history of bilateral cooperation on a range of space projects. This paper discusses the novel interdependencies between clear national and now supranational space policies, using the examples of the Canada-European Union (EU) Comprehensive Economic and Trade Agreement (CETA). The agreement covers most aspects of the EU-Canada bilateral economic relationship and includes space. The paper focuses on international space policies, strategic bilateral co-operation, and technical accomplishments. It takes a closer look at German-Canadian collaboration in space programs and offers some reflection on the effect of both the EU and ESA's transatlantic involvement in space. [ABSTRACT FROM AUTHOR]

This paper looks in retrospect at how the theory of struggle for superiority in the air evolved, and highlights the contribution of Giulio Douhet, founder of the modern air warfare teaching, to the development of this theory. It lists the main factors that determine the substance of struggle for superiority in the air, and forecasts the long-term development of the struggle for superiority in aerospace. It also formulates the chief conditions of attaining strategic superiority in the air and suggests indices and criteria for estimating the degree of dominance in the air and in aerospace. [ABSTRACT FROM AUTHOR]

A helicopter flying through an atmosphere containing particulates may accumulate high electrostatic charges which can challenge its operational safety. In this paper we elaborate and validate a triboelectric charging model to predict the electrification experienced by a helicopter while hovering in dusty air. We employed Large Eddy simulations to describe the turbulent structures inherent in the flow around the rotorcraft. The dust particles were tracked individually in a Lagrangian framework. A model accounting for the triboelectric charge transfer when a particle hits the helicopter was introduced. The results demonstrate the accuracy of the proposed approach and allow a detailed analysis of the location of the charge accumulation. [ABSTRACT FROM AUTHOR]

This paper presents a closed-loop flux-weakening controller for hybrid-excitation synchronous machine drives based on separate regulation of amplitude and phase angle of the armature voltage. Operating point analysis is carried out to investigate the dynamic properties of the drive and to give guidelines in the tuning of the controller. Finally, experimental tests validating the theoretical derivations are performed on a prototype hybrid-excitation drive. [ABSTRACT FROM PUBLISHER]

Abstract: This paper presents the concept of hybrid semantic-document models to aid information management when using standards for complex technical domains. These standards are traditionally text based documents for human interpretation, but prose sections can often be ambiguous and can lead to discrepancies. Many organisations will produce semantic representations of the material. In developing these semantic representations, no relationship is maintained to the original prose. Maintaining the relationships has key benefits, including assessing conformance at a semantic level rather than prose, and enabling original content authors to explicitly define their intentions. This paper proposes a framework to help achieve these benefits. [Copyright &y& Elsevier]

The present paper describes the failure analysis of an aircraft component subjected to several episodes of in service failure, resulted in loss of the aircraft safety. Modern aircrafts are provided with mechanical systems which have the task to open not pressurized hatches during landing. The components of such systems are subject to considerable mechanical stresses in harsh environment (presence of moisture and pollutants, significant and sudden temperature variations). The system is constituted by a sliding piston, a related nipple and by a locking system consisting of 4 steel spheres which are forced into a countersink machined on the piston when the hatches is open. The whole system is activated by a preloaded spring. The machined parts, nipple and piston, are made of EN3358 steel (X3CrNiMo13-8-2), a precipitation hardening stainless steel with very low content of carbon often used in the aerospace. The samples provided by the manufacturer present different types of damage all referable to phenomena relative to the sliding of the piston inside the nipple. The present paper describes the different damage observed and the microstructure of the material, then are reported the results obtained from the characterization of the material of the samples by means of optical and electronic microscopy, carried out to define the mechanisms involved in the system seizure. In order to define the primary cause of failure and to propose solutions to be adopted, also analyzing the criticality of using this PH stainless steel for this application, the results of different tests were compared with system design and working data. [ABSTRACT FROM AUTHOR]

Aerospace thin-walled parts have a complex structure and high accuracy. Factors such as original residual stress, fixing, and machining may make low-rigidity parts deform easily, which is difficult for traditional craftwork to forecast and control. Especially in machining big aerospace parts, original residual stress has a great effect on machining deflection. In this paper finite element model of original residual stress is established to analyze the corresponding deflection by machining aerospace thin-walled parts. Simulation results are validated consistent with experimental results approximately. At last the paper puts forward the corresponding mend methods to control the deflection caused by original residual stress during the actual machining process. [ABSTRACT FROM AUTHOR]

Abstract: Throughout the field of transportation and vehicle systems control is gaining importance. This paper focuses on the current key problems engineers in this field are facing and highlights some major recent accomplishments. The driving forces behind the increasing use of control are the rising need for transportation services and the demand for a higher safety level. While each domain takes specific approach to deal with these demands, a general trend towards automatic co-pilots or even autopilots is visible. In the automotive domain, this is aided by the design of drive by wire systems. In other fields like marine or aerospace systems, the focus of research is on the swarming behavior of multiple vessels. New sensors and networking will also enable more efficient traffic flow control which will allow for a better use of the resource network capacity. Another trend in the vehicle systems sector is the modeling of nonlinear system behavior which is starting to replace look-up tables in real time systems. A forecast on future trends is given at the end of the paper. [Copyright &y& Elsevier]

Abstract: It is well known that among the first motivations for modern control theory were dynamic optimization problems in rocket launching and navigation in aerospace. These problems had become especially important in the 1940s and 1950s due to requirement to minimize various costly resources and design parameters, such as flight time, amount (mass) of fuel, weight of the spacecraft, the drag forces and other items. This had to be done under various restrictions on control capacities and other complicating factors, such for example, as incomplete information on the system. Among the precious techniques of applied mathematics there had long been developed an adequate tool for such problems which is the Calculus of Variations. Problems in flight dynamics had become the earliest serious technical object for its application. A large number of new basic ideas for adapting Calculus of Variations to modern control problems and synthesizing them into modern control theory were elaborated in the course of investigations in flight dynamics. This presentation traces some seminal investigations, which were crucial for related theoretical developments in former Soviet Union and present Russia and had also influenced related research beyond national borders. Such investigations had good historical precursors in the earlier mathematical works of P.L. Chebyshev, A.M. Lyapunov, A.A. Markov, the works in mechanics by N.E. Zhukovski and S.A. Chaplygin and the activities in dynamic systems theory of the 1930s (A.A. Andronov, L.S. Pontryagin, et al.). The present paper is confined only to deterministic problems in trajectory analysis, control and optimization within the framework of mathematical theory of controlled processes. The national community of researchers involved in these topics was enormous, including those in the Academy of Sciences, the Universities and the numerous institutions and plants supervised by related industrial ministries. While giving tribute to all those involved, this paper does not claim to give a full review of available publications, concentrating on what the authors believe to be the seminal issues in the field. This publication will therefore inevitably have a subjective flavor. We sincerely apologize to all those whose contributions may have been missed. [Copyright &y& Elsevier]

The aerospace industry is increasingly transitioning from hydraulic and pneumatic drives to power-electronic based drive systems for reduced weight and maintenance. Electromechanical thrust reverse actuation systems (EM-TRAS) are currently being considered as a replacement for mechanical based TRAS for future aircraft. An EM-TRAS consists of one or more power-electronic drives, electrical motors, and gear-trains that extend/retract mechanical members to produce a drag force that decelerates the aircraft upon landing. The use of a single ("central") power electronic converter to simultaneously control a set of parallel induction machines is a potentially inexpensive and robust method for implementing EM-TRAS. However, because the electrical motors may experience different shaft torques—arising from differences in wind forces and a flexible nacelle—a method to implement rotor position synchronization in central-converter multi-motor (CCMM) architectures is needed. This paper introduces a novel method for achieving position synchronization within CCMM architecture by using closed-loop feedback of variable stator resistances in parallel induction machines. The feasibility of the method is demonstrated in several case studies using electromagnetic transient simulation on a set of parallel induction machines experiencing different load torque conditions, with the central converter implementing both voltage-based and current-based primary control strategies. The key result of the paper is that the CCMM architecture with proposed feedback control strategy is shown in these case studies to dynamically drive the position synchronization error to zero. The initial findings indicate that the CCMM architecture with induction motors may be a viable option for implementing EM-TRAS in future aircraft. [ABSTRACT FROM AUTHOR]

Carbon fibre and carbon fibre reinforced polymer matrix composites (CFRPs) are important lightweight materials for aerospace, automotive, rail transport, infrastructure, and renewable energy applications. This paper provides a comprehensive review on the history of carbon fibres and carbon fibre composites, the current global CFRPs consumption, and trends for future developments in the aerospace, wind turbine, automotive, pressure vessels, sports and leisure, and construction sectors. The history of carbon fibres and CFRPs is discussed over four representative periods including their early development (1950–60's), growth of carbon fibre composites industry (1970–80's), major adoption of carbon fibre composites (the first wave, 1990–2000's), and expanded use of carbon fibre composites (the second wave, 2010's and beyond). Despite a 37% decline of carbon fibre consumption in the aerospace industry in 2021 caused by COVID-19, the global CFRP demand was around 181 kt which more than doubled its value in 2014. There is tangible projected increase over the next five years and the demand for CFRPs is expected to reach 285 kt in 2025, mainly attributed from the fast expansion of non-aerospace industries such as the wind energy sector. Lower cost carbon fibres (e.g., large tow) and associated manufacturing technologies are continually evolving. Finally, the implications of emerging materials and manufacturing methods in conjunction with recycling and reuse for carbon fibre composites are discussed. [ABSTRACT FROM AUTHOR]

The GPS is a satellite navigation system that provides location and time information. Such a system currently supports critical applications for military, civil and commercial users worldwide and is accessible to any operator by using a single GPS receiver. However, although being too dependent on GPS signals, just a few of these applications present some kind of countermeasure to electromagnetic attacks, showing a high level of vulnerability to intentional attacks. In this paper, we pose questions and situations related to security and vulnerability of different kinds of platforms/vectors and systems which directly afflict the situational awareness of operators. Experiments were made with different general GPS receivers as a function of distance and incidence angle, showing that they fail to work even at low jamming powers (-25 and 0 dBm at 10 m). More complex GPS systems, such as aeronautical receivers, were also tested, losing completely the tracking at -30 dBm, when a 0° (levelled) and 10 m far electromagnetic jamming signal is incident on its antenna. A specific open source, free software (JammPy) allows extending these experimental results, providing a roadmap and estimating how much jamming power is necessary to cause damage to these systems. [ABSTRACT FROM AUTHOR]

This paper proposes and investigates an analytical method for assessing the risk of potential irreversible demagnetization in the permanent magnets (PMs) of electrical machines equipped with $n$ -stages, Halbach arrays. The higher risk of demagnetization, synonymous with Halbach arrays, imposes that the method be both load and temperature dependent. In fact, the proposed method studies the magnetic field distribution in the air gap and PM region, for various operating temperatures and expresses these fields as analytical expressions for the no-load and peak-load conditions. The model can cater for Halbach arrays with up to $n$ stages, thus making it a versatile tool that can be utilized for various Halbach configurations. Finite-element analysis is used to validate the method. The analytical tool is then used for the design and analysis of a high torque density, outer rotor, traction motor. The motor is for an aerospace application and its operating duty cycle imposes very high, short-time, peak-load conditions at elevated temperatures, posing an elevated risk of irreversible PM demagnetization. The model is used to investigate various Halbach configurations for this application, in order to reduce the demagnetization risk and also to improve the general performance of the machine. The analytical method thus provides a computationally efficient tool that can be used to predict and prevent demagnetization in Halbach-equipped electrical machines operating in harsh environments such as the aerospace sector. [ABSTRACT FROM AUTHOR]

In-service structural health monitoring of composite aircraft structures plays a key role in the assessment of their performance and integrity. In recent years, Fibre Optic Sensors (FOS) have proved to be a potentially excellent technique for real-time in-situ monitoring of these structures due to their numerous advantages, such as immunity to electromagnetic interference, small size, light weight, durability, and high bandwidth, which allows a great number of sensors to operate in the same system, and the possibility to be integrated within the material. However, more effort is still needed to bring the technology to a fully mature readiness level. In this paper, recent research and applications in structural health monitoring of composite aircraft structures using FOS have been critically reviewed, considering both the multi-point and distributed sensing techniques. [ABSTRACT FROM AUTHOR]

In this paper the correlation of deformation energy and critical buckling loads is examined. An advanced analysis technique is derived for the investigation of z-section frames typically applied in composite aircraft fuselage. This technique is verified through closed form solutions of z-section columns under quasi-static loading conditions. The method is applied to study the effects of flange width and laminate thickness on the critical failure modes of composite frames. Therein, the focus is on composite structural elements favourable for deformation kinematics in aerospace applications subjected to crash loads. [ABSTRACT FROM AUTHOR]

This paper reports a propulsion motor for a solar-powered aircraft. The motor uses precompressed aluminum stator windings, with a fill factor of greater than 75%, in a permanent magnet synchronous machine. The motor performance is compared empirically to an identical machine with conventionally wound copper windings. It is shown that there are many advantages to using compressed aluminum windings in terms of weight reduction, thermal improvement, and lower cost, for the same loss and electromagnetic performance, provided a sufficiently high slot fill factor can be achieved. The design and manufacture of the compressed coils is also discussed. A modular stator arrangement is used, in the form of a solid coreback with keyed teeth to allow easy assembly of the compressed windings. It is noted that the electromagnetic performance of the machine is unaffected by the modular nature of the magnetic core. Two prototype motors, one wound with conventional copper and the other with precompressed aluminum windings, are constructed and tested. [ABSTRACT FROM PUBLISHER]

• A novel space deployable structure with curved surface by employing the origami design concept is proposed. • Programmability and kinematic performance of the thick-panel origami network are illustrated. • A comprehensive quantitative design method to achieve a specific deployable status is established. • Two sample prototypes of a circular cylindrical antenna and a parabolic antenna are manufactured to verify the design concept and exhibit potential applications. Space deployable structures are widely used in multiple space missions, and origami-inspired design is becoming a prevalent method to create deployable structures with innovative folding concepts. This paper proposed a novel space deployable structure with curved surface by employing the origami design, which is generated by strategically integrating two types of plane-symmetric thick-panel origami modules and the formation of network is described in detail. By taking advantage of the kinematic programmability, this origami-based deployable structure can be utilized to construct different target configurations, such as circular cylindrical surface and parabolic surface. Geometric analysis of the origami-inspired deployable structure are provided, as well as a comprehensive quantitative design method to customize a specific deployable status. Furthermore, two sample prototypes of a circular cylindrical antenna and a parabolic antenna are manufactured to verify and exhibit the potential applications of the origami-based deployable structures. This study provides a new approach to construct space deployable structures with different curved surfaces for aerospace engineering applications. [ABSTRACT FROM AUTHOR]

Abstract: Aircraft pitot-static probes are essential to airspeed and altitude measurements and safe flight. Measurement integrity is typically achieved via sensor hardware redundancy and a voting system. Hardware redundancy imposes a cost and payload penalty. This paper investigates an analytical alternative to hardware redundancy requiring a mathematical model of faulted and unfaulted pitot-static probes. The most common probe faults–debris, ice, or water blockages–are modeled using physical air data relationships and experimental wind tunnel data. These models are used with a linear model of the NASA GTM aircraft at one flight condition to design robust fault detection filters. Two linear filters are designed to detect faults, reject disturbances, and provide robustness to model errors. Performance is evaluated using experimentally derived fault models with nonlinear aircraft simulations that incorporate actuator uncertainty. [Copyright &y& Elsevier]

Directed Infrared Countermeasures (DIRCM) are used to protect aircrafts against missiles with infrared (IR) guidance. They are employed by military and civilian aircrafts, drawing away the guidance system of a missile as it attempts to lock onto the IR signature of the turbines. Unfortunately, the protection provided by these devices generates risks and challenges that must be overcome. In this paper, investigations on DIRCM risks to fighter aircraft pilots are carried out. Different kinds of lasers employed in actual DIRCMs are analyzed and the results show that, depending on their frequency (wavelength), damages can occur up to a distance of 4.8 km. The transmittance through the canopy of an F-5 fighter aircraft is evaluated and its effects on the IR propagation are predicted by the use of software called Counter-Measurements in PYTHON (CMePy). Results show that, even when there are interfaces between the pilot and the source of radiation, damages can occur, showing the importance of this investigation to the right understanding of this subject and future mitigations. [ABSTRACT FROM AUTHOR]