Australian Defence Force Academy

Drones have long been explored by commercial and military users for supply. While several systems offering small payloads 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, we evaluate these challenges from a conceptual modelling perspective and forecast their applicability once these barriers are overcome. This study uses technology trend modelling and bibliometric activity mapping methodologies to predict the applicability of specific technologies that are currently identified as operational challenges. Specifically for supply drones, we model trends in technological improvements of battery technology and aircraft control, and project its 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 constraints of larger supply drones. A case study involving the 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.

The Boundary Layer Transition (BOLT) flight experiments were developed to study hypersonic boundary-layer transition and turbulence on an experimental configuration featuring low-curvature concave surfaces and highly swept leading edges. Building upon the BOLT-1A mission, the follow-on BOLT-1B flight experiment was successfully launched on September 2, 2024, from Andøya Space, Norway. This paper presents results from time- and frequency-domain analysis of wall-pressure measurements acquired on the primary surface of the BOLT-1B vehicle during both the ascent and descent experiment windows. Time-series data from Kulite pressure transducers revealed spatial variations in the onset and delay of boundary-layer transition and re-laminarization, depending on each sensor’s distance from the leading edge. The corresponding energy spectra exhibited a characteristic $-7/3$ slope within the inertial frequency range; however, finite differences in energy distribution were observed between the ascent and descent phases, which are believed to be an effect of local Reynolds number at the Kulite sensor locations. Time–frequency analysis of pressure fluctuations from PCB sensors located near the swept edges show broadband energy spectra indicating turbulent flow at those locations, while the sensors closer to the centreline show second mode instabilities associated with transition/re-laminarisation. Further, there is a redistribution of spectral energy to lower frequencies during the re-laminarization process of turbulent flow near the swept edges, which requires further investigation.

Given the increasing number and severity of cyber attacks, there has been a surge in cybersecurity information across various mediums such as posts, news articles, reports, and other resources. Cyber Threat Intelligence (CTI) involves processing data from these cybersecurity sources, enabling professionals and organizations to gain valuable insights. However, with the rapid dissemination of cybersecurity information, the inclusion of fake CTI can lead to severe consequences, including data poisoning attacks. To address this challenge, we have implemented a three-step strategy: generating synthetic CTI, evaluating the quality of the generated CTI, and detecting fake CTI. Unlike other subdomains, such as fake COVID news detection, there is currently no publicly available dataset specifically tailored for fake CTI detection research. To address this gap, we first establish a reliable groundtruth dataset by utilizing domain-specific cybersecurity data to fine-tune a Large Language Model (LLM) for synthetic CTI generation. We then employ crowdsourcing techniques and advanced synthetic data verification methods to evaluate the quality of the generated dataset, introducing a novel evaluation methodology that combines quantitative and qualitative approaches. Our comprehensive evaluation reveals that the generated CTI cannot be distinguished from genuine CTI by human annotators, regardless of their computer science background, demonstrating the effectiveness of our generation approach. We benchmark various misinformation detection techniques against our groundtruth dataset to establish baseline performance metrics for identifying fake CTI. By leveraging existing techniques and adapting them to the context of fake CTI detection, we provide a foundation for future research in this critical field. To facilitate further research, we make our code, dataset, and experimental results publicly available on GitHub.

The transition to electric aircraft for zero-emission transport requires integrating thermal management systems for high-performance batteries without incurring significant weight, balance, or aerodynamic penalties. This study focuses on the aerodynamic penalties associated with air-cooling systems that can compound the presently unavoidable reduction in endurance imposed by current battery energy density limitations. Building on previous research into battery installation layouts and internal cooling flows, this study is the first to investigate the lift-to-drag (L/D) optimisation for the multiple wing-mounted inlets and outlets necessary for air-cooling batteries in the wing of an electrified aircraft. Wing leading-edge inlets and NACA (National Advisory Committee for Aeronautics) ducts were analysed by systematically varying their layout, number, and dimensions. The analysis evaluated their effects on the wing’s lift, drag, and moment to maximise the L/D. Multiple highly efficient simulation test designs were developed to screen for the main factors to identify the best inlet and outlet configuration, resulting in 66 different Computational Fluid Dynamics (CFD) simulations in Ansys Fluent. Following this, three CFD verification cases of the best configuration were conducted to verify the cooling effect by combining both internal and external flow simulations with heat generation. Compared to the baseline wing of the carbon combustion aircraft, the best configuration caused a 1.75% reduction in L/D, range, and endurance. While the aerodynamic penalty is now minimised, the internal battery pack layout requires further optimisation to re-establish uniform cooling across the battery pack. Designers may still be able to separate the CFD analysis of the internal and external flow regimes with idealised inlets and outlets; however, more whole-field CFD iterations are needed to guide such subdivision to a viable and safe design for wing-mounted batteries. Further, the margins are such that wing-mounted electrification warrants careful instrumented validation in an aircraft. These findings provide crucial design guidance for sustainable aviation, particularly to enable after-market electrification projects.

We obtain several new bounds on exponents of interest in analytic number theory, including four new exponent pairs, new zero density estimates for the Riemann zeta-function, and new estimates for the additive energy of zeroes of the Riemann zeta-function. These results were obtained by creating the Analytic Number Theory Exponent Database to collect results and relationships between these exponents, and then systematically optimising these relationships to obtain the new bounds. We welcome further contributions to the database, which aims to allow easy conversion of new bounds on these exponents into optimised bounds on other related exponents of interest.

Graph matching, as an important query technology, has been widely applied in various fields. With the increasing of graph data, users choose to encrypt a large number of graphs and store them in the cloud. Existing solutions to graph matching query over encrypted graphs require the user to execute a lot of time-consuming subgraph isomorphism (NP-complete problem) operations to extract the matched graphs, which inevitably brings heavy computational burden to the user. Therefore, how to reduce the number of subgraph isomorphisms is crucial for releasing the user from the heavy workload in a graph matching query scheme over encrypted graphs. In this paper, we propose a secure and efficient scheme for graph matching query over encrypted graphs. The main idea is to classify the query graph into frequent subgraph and infrequent subgraph, and adopt different strategies to perform the matching query. We design the novel secure index based on the frequent subgraphs and the edge labels to reduce the number of subgraph isomorphisms. When the query graph is a frequent subgraph, the proposed scheme can directly produce the exact result owing to this secure index. The user does not need to perform any subgraph isomorphism in this case. When the query graph is an infrequent subgraph, the proposed scheme can return a set of data graphs very close to the exact result. As a result, the proposed scheme reduces the number of subgraph isomorphisms substantially. Formal security proof is provided. Extensive experiments on real-world data sets show that the proposed scheme reduces nearly 90% subgraph isomorphism.

Abstract Hot subdwarf B stars (sdBs) are helium-burning stars with thin hydrogen-rich envelopes. Their most widely accepted formation channels involve binary evolution and progenitors near the tip of the red giant branch, thus studying these objects improves our knowledge of complicated astrophysical processes such as common envelope evolution and the helium flash. In this work, we compare the observed sdB population against a synthetic Galactic population generated through the binary population synthesis code compas, which allows us to estimate the physical properties of the current-day Galactic sdB population. We show that our synthetic sdB population matches the general properties of the observations quite well in the Kiel diagram when either a normal or log-normal distribution is assumed for the assignment of hydrogen-rich envelope masses. We also find that the canonical mass assumption should only be confidently assumed for specific system configurations and that the estimated number of sdBs found within 500 pc of the Sun in our model is at least four times higher than the observational one. We recover the observational P-q relation for sdBs plus main sequence companions, while a similar relation between sdBs and helium white dwarf companions is rather complicated. We conclude that a better understanding of hydrogen-rich envelopes is needed, as well as an observational characterization of the sdB plus main sequence companions earlier than spectral type ∼ F. These issues aside, atmospheric properties, companion types, period and mass distributions are in good agreement with observational and theoretical studies available in the literature.

We present the most extensive set to date of high-quality RR Lyrae light curve templates in the ɡriz bands, based on time-series observations of the Dark Energy Camera Plane Survey (DECaPS) East field, located in the Galactic bulge at coordinates (RA, Dec)(J2000) = (18:03:34, −29:32:02), obtained with the Dark Energy Camera (DECam) on the 4-m Blanco telescope at the Cerro Tololo Inter-American Observatory (CTIO). Our templates, which cover both fundamental-mode (RRab) and first-overtone (RRc) pulsators, can be especially useful when there is insufficient data for accurately calculating the average magnitudes and colors, hence distances, as well as to inform multiband light curve classifiers, as will be required in the case of the Vera C. Rubin Observatory’s Legacy Survey of Space and Time (LSST). In this paper, we describe in detail the procedures that were adopted in producing these templates, including a novel approach to account for the presence of outliers in photometry. Our final sample comprises 136 RRab and 144 RRc templates, all of which are publicly available. Lastly, in this paper we study the inferred Fourier parameters and other light curve descriptors, including rise time, skewness, and kurtosis, as well as their correlations with the pulsation mode, period, and effective wavelength.

Blockchain technology, renowned for its robust security and immutability, places the responsibility of safeguarding credentials on users. However, the loss of cryptographic keys and credentials without recovery methods poses significant challenges in accessing wallets and reclaiming blockchain identities. Digital wallets are crucial for identity management and secure administration of cryptographic keys and credentials. This paper introduces an optimized key recovery model for blockchain-based digital wallets, leveraging a cascade blockchain framework to facilitate wallet recovery through seed phrases. The study aims to empower stakeholders by providing them with themeans to regain control over their credentials, thereby enhancing security and resilience in Supply Chain Management practices.

This paper examines the legal basis and framework for the United Nations registration process for space objects. UN registration processes are compared against and contrasted with national and regional registration processes to highlight potential adjustments in light of the need for a space traffic management system. While there are shortfalls in compliance and monitoring of States’ responsibility to adhere to UN registration requirements, the growing importance of space traffic management is providing a catalyst for reform and recommitment to the ideals upon which the 1975 UN Registration Convention was based. Since the data provided to national registries and the UN register is not detailed enough and is not sufficient for creating a space traffic management regime, it is recommended that (1) the recommendations concerning the registration of space objects belonging to a large constellation that were agreed by the UNCOPUOS Working Group on the Status and Application of the Five United Nations Treaties on Outer Space in 2023 are implemented to ensure uniformity of registration practice regarding large constellations; (2) States incentivize good registration practices by other States, for instance by requiring that satellites of commercial actors are registered by the relevant launching State as a condition for market access; (3) the importance of furnishing additional information on the subsequent activity and status of objects, as required by the Registration Convention, UN General Assembly resolutions 1721 (XVI) B and 62/101 and Guideline A.5 para 2 of the UNCOPUOS Guidelines on the Long-Term Sustainability of Space Activities, be underlined.