Search Results (412)

Modern intrusion detection systems (IDSs) are often evaluated under matched training and test conditions, whereas deployment environments involve changing traffic distributions, heterogeneous feature-generation pipelines, and shifting attack prevalence. This study investigates benchmark-shift-aware intrusion detection through harmonized cross-dataset evaluation of HIKARI-2021, CICIDS2017, and a CICIoT2023 sample subset. Two payload-free feature spaces are constructed: Rich-64 for detailed HIKARI-2021/CICIDS2017 analysis and Minimal-13 for three-way comparison. Using XGBoost, a supervised Transformer, and a masked-feature self-supervised Transformer, we evaluate discrimination, calibration, threshold transfer, alert-budget behavior, chronological robustness, and score-orientation stability. Across five in-domain XGBoost settings, observed false-positive rates were 4.94–5.40%, and F1-scores ranged from 0.507 to 0.995. Under strict Rich-64 HIKARI-2021-to-CICIDS2017 transfer, all models had zero recall at source-derived thresholds, with two showing inverted score orientation. In the reverse direction, XGBoost reached an 18.9% target false-positive rate, while a nominal 5% target-side alert budget yielded F1 = 0.112. Chronological evaluation further showed that improved ranking metrics did not guarantee stable validation-derived operating behavior. The study provides a reproducible diagnostic framework for evaluating IDS robustness under evolving benchmark conditions. Full article

Large-scale maritime activity, persistent shipping incidents, and complex marine environments continue to place substantial demands on maritime search and rescue (MSAR). Current MSAR systems do not fully capitalize on the complementary strengths of unmanned aerial vehicles (UAVs) and satellites for collaborative tracking and rescue support. Existing air-space collaboration technologies suffer from two critical limitations: (1) rigid processes, including fixed task allocation, pre-determined path planning without real-time environmental adaptation, and isolated satellite–UAV decision-making, and (2) long task completion cycles, mainly because many methods are adapted to wide-area, long-duration military tracking scenarios. They therefore provide limited support for the dynamic flexibility required in MSAR. This study proposes a Proximal Policy Optimization (PPO)-based air-space collaborative tracking method for maritime moving targets to address these shortcomings and enhance air-space cooperation in MSAR operations. The core implementation of the method includes: (1) integration of target drift forecasting, satellite orbit prediction, UAV task allocation, and path planning into a unified reinforcement learning framework to reduce isolated single-platform decision-making; (2) the adoption of PPO to generate dynamic and flexible air-space collaborative tracking strategies that adjust satellite observation angles and scanning ranges, as well as UAV altitude, speed, and heading according to real-time target, environmental, and platform states; and (3) the design of a multi-dimensional reward function that balances target proximity, energy efficiency, coverage overlap, and inter-platform cooperation to guide strategy optimization. Simulation experiments include system-feasibility verification, baseline-controller comparison, PPO hyperparameter screening, and cross-scenario evaluation. Under idealized communication and payload-matching assumptions, the method enables coordinated tracking of maritime moving targets in simulated MSAR scenarios. In the standardized evaluation, PPO achieved an 11.9% higher mean evaluation episode return, 11.2% lower aggregate UAV energy consumption, and a 9.92-percentage-point greater endurance margin than DDPG. Hyperparameter screening compared candidate learning rates, discount factors, and training budgets, informing the PPO configuration for the subsequent six-scenario evaluation. Across the six controlled scenarios, rewards stabilized after approximately 1400 steps, while action magnitudes varied among regions. These results indicate that the proposed method has potential to enhance air-space collaborative tracking for MSAR decision support. Full article

Unmanned aerial vehicles (UAVs) used in low-altitude mobility and electric aviation are increasingly required to carry higher payloads, operate for longer durations and maintain reliable performance under constrained installation conditions. In compact power cabins, batteries, controllers, power distribution units and auxiliary actuators are densely arranged, making cabin thermal management a critical design issue. In this study, a full-scale conjugate flow and heat transfer model is developed for the power cabin of a UAV and validated against thermal management experiments. The validated model is then used to examine how a conventional rectangular ram-air inlet and a proposed stepped ram-air inlet affect air capture, internal flow organization and temperature distribution. The inlet area of the rectangular configuration is first varied to establish a baseline, after which the transition arc ratio, spacing ratio and area ratio of the stepped inlet are parametrically investigated. The results show that increasing the rectangular inlet area from 0.002 to 0.008 m² increases the total captured mass flow rate from 0.258 to 1.084 kg/s, whereas the cabin average temperature decreases by 0.34 °C. By contrast, the cabin maximum temperature decreases nonlinearly, with a 27.2% reduction when the area increases from 0.004 to 0.006 m². These results indicate that air capture and the cabin average temperature alone are insufficient to evaluate cooling effectiveness in a compact multi-source cabin. For the stepped inlet, the transition arc ratio controls the turning of the incoming flow, the spacing ratio governs shielding and backflow between adjacent inlet sections, and the area ratio redistributes the dominant inlet sections. The best-performing stepped-inlet configuration among the tested cases increases the captured mass flow rate by 32.8% compared with the rectangular baseline under the same opening constraint and improves the utilization of cooling air around high heat load components. This study demonstrates that ram-air inlet design for UAV power cabins should be treated as a coupled problem of the mass flow capture, internal flow path and component-level thermal response. Full article

Periodontitis and dental caries remain among the most prevalent chronic diseases, and their local treatment is limited less by the choice of active agent than by the difficulty of sustaining therapeutic concentrations against salivary and crevicular clearance, the mucosal barrier and the biofilm matrix. This narrative review (PubMed/MEDLINE, Scopus, Web of Science; 2010–2026; 118 sources) maps five mechanistic classes—mucoadhesive, in situ gelling, stimuli-responsive, nano-/microparticulate and biomimetic—alongside marketed sustained-release products onto the specific barrier each addresses and onto an explicit translational gradient. The barriers are quantified rather than described: a pocket of ≈0.5 µL perfused at ≈20 µL/h turns over some 40 times hourly, giving an intra-crevicular half-life of about one minute, and the inflamed pocket is neutral-to-alkaline (pH 7.4–8.5), so acid-triggered release is a cariogenic and not a periodontal strategy, whereas alkaline-triggered release remains an open design space. A dose calculation from these figures identifies payload potency and deliverable mass, not carrier retention, as the binding constraint on phytocompound delivery. Because no single class overcomes all barriers, hybrid nano-in-macro architectures are analysed as the structural solution. Measured against a marketed benchmark of ≈0.3 mm additional probing-depth reduction, progress now depends on consolidation rather than on novelty. Full article

High-mobility dual-functional radar–communication systems require a common waveform that combines delay–Doppler information organization, sensing resolution, and power-efficient transmission. We present a cyclically closed constant-envelope orthogonal time frequency space–continuous phase modulation–linear frequency modulation (OTFS–CPM–LFM) waveform and matched transceiver architecture. Hermitian delay–Doppler mapping and direct-current (DC) row nulling create a real, zero-sum drive with a reversible frame-level phase representation. The communication receiver combines a Tikhonov-regularized waveform inverse with reference-aided unwrapping and tail-biting phase regression, while the radar receiver reconstructs the data-dependent current-frame reference. Numerical results verify the structural waveform properties and characterize communication, radar, and computational tradeoffs. They also quantify degradation under controlled complex-gain channel-state-information mismatch and show that phase regression is less reliable at a low signal-to-noise ratio (SNR). The constant-envelope claim applies only to ideal discrete complex-baseband samples and does not include pulse shaping or radio-frequency hardware. The framework therefore provides a self-consistent waveform interface while exposing tradeoffs among payload, recovery reliability, sensing sidelobes, and implementation cost. Full article

The foundation of modern vehicle control relies on Electronic Control Units (ECUs) communicating via the Controller Area Network (CAN). However, CAN was not designed with security in mind. Limited bandwidth and lack of security make CAN vulnerable, while centralized solutions like AUTOSAR SecOC suffer from high latency. To solve this problem, we propose a novel security protocol named Self-Updating Hash Chain Layered Security Protocol (SUHC-LSP), which uses a “space-time coupled” frame structure to fit a robust authentication code into the limited CAN data field. Unlike conventional schemes that require explicit freshness negotiation during routine operation, SUHC-LSP adopts a self-updating hash-chain mechanism in which chain evolution proceeds autonomously under normal conditions. In addition, SUHC-LSP introduces a self-updating hash chain mechanism that enables freshness iteration during steady-state operation. Traditional AUTOSAR SecOC configuration schemes require additional synchronization messages and freshness counter management, whereas the approach proposed in this paper eliminates the resulting bandwidth overhead while adhering to the 8-byte CAN payload limit and ensuring message authenticity and integrity. In addition, a risk-adaptive two-layer architecture is designed to balance fast speed for local messages and strong encryption for cross-domain messages. BAN-logic and ProVerif verification show that the protocol preserves authentication, freshness, secrecy, and event-correspondence properties under the stated assumptions. Experiments on an STM32 platform show that, in a 4-device prototype, the computational overheads are 1.61 ms for intra-domain communication and 0.83 ms for inter-domain communication. Moreover, analytical overhead comparison indicates that the proposed protocol has lower sensitivity to network scale than the compared schemes. Full article

High-rise building fires pose substantial challenges to conventional firefighting operations due to restricted rescue space and the difficulty of delivering suppression resources rapidly. To improve response efficiency, this study proposes a two-stage mission planning framework for multi-station UAV-based firefighting. The proposed methodology simultaneously accounts for environmental wind, building obstacles, fire evolution, and UAV payload constraints. In the first stage, an improved particle swarm optimization (PSO) algorithm is employed to generate time-optimal flight paths satisfying both spatial obstacle-avoidance and wind-field constraints. In the second stage, based on the actual flight times derived from the first stage, the multi-UAV resource scheduling problem is formulated as a mixed-integer linear programming (MILP) model to minimize the total fire suppression mission duration. Additionally, an isochrone-based firefighting coverage circle is introduced to optimize the layout of additional fire stations. Simulation results indicate that while optimized paths remain geometrically similar under varying wind conditions, wind-induced flight time variations significantly affect UAV arrival sequences and flight times. In the scheduling stage, differences in station layouts and fire scales alter projectile release timing; under unfavorable conditions, such temporal differences can increase the total mission duration by more than 28%. Notably, the optimized addition of fire stations effectively enhances response redundancy in high-rise clusters, reducing fire suppression time in adjacent scenarios by approximately 50%. The proposed method provides theoretical support and methodological guidance for cooperative UAV firefighting and emergency resource optimization in urban environments. Full article

Traditional Low Earth Orbit (LEO) satellite constellation design methods, primarily driven by geometric coverage, fail to satisfy the non-uniform and dynamic tracking requirements of moving targets. To address this, a multi-objective optimization framework for large-scale satellite constellations is proposed. This framework is task-driven, constraint-guided, and integrates space and ground segments. A quantitative model is established to characterize the multi-target tracking capability of space-based sensing systems. The model explicitly links the constellation revisit period, payload detection and positioning performance, target maneuverability, and the maximum trackable target density. These relationships are then formulated as optimization objectives and constraints. To capture temporal consistency in observation performance, the coefficient of variation of revisit time is introduced as an independent optimization objective. This yields a three-objective optimization problem that addresses tracking performance, coverage uniformity, and system cost, enabling Pareto-optimal constellation design solutions. Simulation results demonstrate that the proposed method improves track association performance in representative maritime target tracking scenarios when compared with conventional coverage-driven constellation designs. The proposed framework provides a systematic and implementable approach for constellation design by integrating capability modeling with multi-objective optimization at the system level. Full article

Attitude determination serves as a critical foundation for spacecraft to accomplish various space missions. The conventional single field-of-view (FOV) operating mode of attitude sensors suffers from inherent observational geometric limitations, resultingin significantly larger errors for the boresight roll angle than for the right ascension and declination attitude axes. This issue severely restricts the application of such sensors in high-precision space missions, including space target positioning and high-resolution remote sensing. Existing multi-FOV joint attitude determination methods address the challenge of three-axis error imbalance through optical system improvements or multi-sensor integration. However, these approaches often involve complex system designs and substantial payload overhead. In this paper, without modifying or adding any optical system, we construct a virtual dual-FOV joint observation scenario by correlating multiple sequentially acquired star images. This strategy effectively mitigates the large deviation of the Z-axis attitude angle and achieves more equalized three-axis error performance. Experimental results demonstrate that under the virtual dual-FOV configuration with a 30° separation angle, the proposed method maintains high measurement accuracy for the right ascension and declination of the camera boresight, while reducing the root-mean-square error of the rotation angle around the boresight direction from 7.0213″ to 1.6398″, corresponding to an improvement of 76.65%. This paper provides a novel technical approach for high-precision, three-axis-equalized attitude determination using single-FOV attitude sensors. Full article

With the increasing softwarization of satellite payloads and the evolution of 6G Non-Terrestrial Networks (NTNs), securing the onboard software supply chain has become critical for mission-critical space communications. Traditional static software composition analysis (SCA) often generates excessive false positives in resource-constrained satellite environments. To address this issue, this paper proposes SSCRPDM, a CVE-oriented static–dynamic risk detection method based on bytecode instrumentation. SSCRPDM parses CVE semantics to guide function-level minimal instrumentation, quantifies risk by jointly considering runtime reachability, parameter controllability, and sanitizer effectiveness, and employs deterministic proof-of-concept (PoC) verification as the primary decision mechanism, with a large language model used only for auxiliary interpretation. Specifically, SCA first identifies components containing known vulnerabilities. Runtime instrumentation then traces critical invocation paths and verifies the reachability of vulnerable functions. Finally, CVE-specific PoC payloads are executed under the current defense context to determine actual exploitability. Experimental results show that SSCRPDM effectively filters alerts caused by “zombie components” and significantly improves evaluation accuracy through exploitability verification. By bridging static version matching and dynamic threat validation, SSCRPDM substantially reduces false positives and provides a precise and proactive solution for satellite software supply chain governance. Full article

Continuous stream-oriented data-plane processing in 5G/6G edge nodes increases the energy and latency cost of CPU-centered execution. This paper studies this boundary on an Intel Cyclone V SoC FPGA and proposes Hardware Accountability: a partitioning discipline in which Linux performs supervisory control while high-rate payload processing remains in programmable logic. The evaluation uses the Strumok stream cipher, adopted as the Ukrainian national standard DSTU 8845:2019, as a secure fronthaul/payload workload with XOR- and shift-dominated logic. On the evaluated USB 2.0/Cortex-A9/Linux path, the software-driven stream approaches saturation near 20 MSPS. In contrast, the RTL core reaches 9.6 Gbps at 150 MHz and occupies less than 6% of the available logic. Quartus Prime vectorless power analysis estimates 24.00 mW dynamic power for the RTL computational core, corresponding to approximately 2.5 pJ/bit. Control-plane measurements show P99 orchestration jitter below 1 ms under Spatial Isolation, conservative full context reloads near 1290 per second, and more than 7200 shadow-register context/state update operations per second. A design-space exploration then projects an 83.2 Gbps multi-core data path when external DDR traffic is avoided through internal stream aggregation and elastic buffering. Full article

In engineering practice, different requirements often give rise to distinct product designs. For the specific case of multi-UUVs, small-scale vehicles are typically designed with a rotational body shape to ensure superior hydrodynamic performance, whereas large-scale vehicles are often configured with a near-rectangular body shape to satisfy the demands of substantial payload capacity. These two tasks share a portion of common variables, while each also maintains its own task-specific variables. When each task is optimized independently, redundant computational efforts are incurred and inherent similarities among tasks remain unexploited, which frequently leads to suboptimal solutions. Typical multitask optimization algorithms assume completely heterogeneous tasks and therefore become inefficient when applied to this kind of partially heterogeneous problem. To address this, a manifold alignment and hierarchical surrogate-assisted transfer optimization algorithm (MAHSTO) is proposed in this work. In MAHSTO, an implicit knowledge transfer strategy is developed via manifold alignment. The design variables of both tasks are mapped onto a common low-dimensional latent space via manifold alignment, which enables implicit knowledge transfer across tasks. In addition, a hierarchical multisurrogate model with adaptive sampling is established. It comprises one shared global surrogate model that captures common trends across tasks and two task-specific surrogate models that focus on accurately fitting their respective tasks. Furthermore, an adaptive sampling criterion is adopted for different surrogate models to balance exploration and exploitation. Experiments on benchmark cases demonstrate that the proposed MAHSTO outperforms four state-of-the-art optimization algorithms, achieving the best performance in 58.3% of cases. Finally, MAHSTO is applied to the shape optimization of multi-UUVs. The results further verify its competitiveness in handling computationally expensive engineering problems. Full article

Space inertial actuators, represented by reaction wheels, momentum wheels, flywheels, and control moment gyroscopes, are indispensable angular-momentum exchange devices in spacecraft attitude determination and control systems. Owing to their non-consumable operation, high reliability, and precise torque-generation capability, these actuators are widely employed for attitude stabilization, rapid attitude maneuvering, payload disturbance mitigation, and precision pointing in modern satellites and space vehicles. With the rapid growth of high-resolution Earth observation missions, deep-space exploration programs, and large-scale commercial satellite constellations, the performance requirements imposed on inertial actuators are becoming increasingly stringent. This paper systematically reviews the current state of the art in space inertial actuator technologies by integrating peer-reviewed research with publicly available industrial product information, and summarizes recent research progress, representative products, and development strategies in the United States, Europe, Russia, and China. By comparing the technical characteristics and evolutionary pathways of mainstream reaction wheel, momentum wheel, flywheel, and control moment gyroscope systems, the study identifies the principal technological drivers shaping future development. The analysis reveals five dominant trends: extended operational lifetime, higher control accuracy, greater torque and angular-momentum density, reduced micro-vibration disturbance, and scalable, cost-effective manufacturing. These findings provide a systematic technical reference for future research, engineering design, and industrial development of advanced space inertial actuator systems in China and internationally, particularly for next-generation spacecraft requiring long service life, high pointing accuracy, low disturbance, and scalable production. Full article

The Chinese Ocean Salinity Mission (COSM) is an ocean observation mission performed by the National Satellite Ocean Application Service (NSOAS), China Academy of Space Technology (CAST) and National Space Science Center (NSSC). It is the first satellite that has been used to obtain global ocean salinity information in China. This article mainly introduces the working principles of the COSM satellite, which are composed of the platform, two payloads, and the components of the ground segment. This article focuses on the structure and layout of the satellite ground segment, as well as its workflow during satellite operation. It also describes the calibration of payloads and the expected ocean salinity products. At present, the status of the COSM is normal, including its satellite and ground segment, and NSOAS has officially released ocean salinity data products from the COSM. Full article

Reliable communication infrastructure is a fundamental component of Intelligent Transport Systems (ITSs), particularly in scenarios involving maritime corridors and emergency traffic management. In locations where optical fiber deployment is geographically constrained, unmanned aerial vehicle (UAV)-assisted free-space optical (FSO) relay links provide a flexible and rapidly deployable alternative. However, atmospheric attenuation, turbulence-induced fading, and wind-induced UAV misalignment can severely degrade link reliability and disrupt real-time transport data streams. This study proposes a payload-efficient multiple-input multiple-output free-space optical (MIMO-FSO) relay architecture based on a multi-output/single-input (MOSI) uplink and a single-output/multi-input (SOMI) downlink. Here, MOSI denotes multiple ground-based transmit apertures directed toward a single UAV receiving aperture, whereas SOMI denotes one UAV transmitting aperture serving multiple ground-based receiving apertures. Unlike conventional symmetric UAV-assisted MIMO-FSO relays that may duplicate diversity hardware on the aerial node, the proposed design shifts the parallel optical branches to the ground stations and keeps only one optical receiver and one optical transmitter on board the UAV. Under the adopted 4 × 4 comparison assumption, this reduces the UAV-side optical branch count from eight to two, corresponding to a 75% branch-count reduction proxy. System performance is evaluated over a 1.54 km relay link. The analytical framework describes Beer–Lambert attenuation, log-normal/gamma–gamma turbulence, and statistical pointing errors; in the OptiSystem implementation, their combined effects are represented by equivalent aggregate losses of 25 dB/km for atmospheric absorption/scattering and 25.5 dB/km for turbulence- and pointing-related degradation. Comparative simulations for SISO, 2 × 2, and 4 × 4 configurations show that the proposed 4 × 4 architecture increases the Q-factor from 8.38 to 18.25 and changes the OptiSystem-reported minimum BER from 2.73 × 10⁻¹⁷ to 9.95 × 10⁻⁷⁵. Because a finite simulation cannot statistically validate error probabilities of this magnitude through raw error counting, values far below 10⁻¹² are interpreted primarily as comparative indicators of receiver decision margin. The findings provide simulation-based evidence that the proposed architecture is a scalable candidate for resilient optical wireless backhaul in smart transport corridors under adverse propagation conditions. Full article