Search Results (364)

Ensuring the reliable, auditable, and privacy-oriented distribution of donations in disaster logistics constitutes a critical challenge due to multi-stakeholder coordination difficulties and the risk of misuse. This study presents a modular architecture, named SecureRelief, operating on a permissioned Hyperledger Fabric platform. The architecture integrates authentication based on Self-Sovereign Identity (SSI), Decentralized Identifiers (DID), and WebAuthn, together with Attribute-Based Access Control (ABAC), and enables the verification of delivery evidence through privacy-preserving validation using zero-knowledge proofs (ZKP). Documents are stored off-chain on the InterPlanetary File System (IPFS), while only cryptographic summary (hash) values sufficient for integrity verification are maintained on-chain. In scenario-based laboratory experiments, the blockchain layer demonstrated low latency (p95 < 16 ms) and stable transaction throughput, confirming its scalability. While the API layer handled high burst request loads with a 0% error rate, the additional computational overhead introduced by the integrated privacy-preserving (ZKP) mechanisms kept the end-to-end transaction latency within acceptable limits for disaster management applications (3.5–4.5 s). Full article

The rapid digitization of library resources has intensified the need for robust digital-rights management (DRM) mechanisms to safeguard copyright, control access, and preserve user privacy. Conventional DRM approaches are often centralized, prone to single-point-of-failure, and are limited in transparency and interoperability. To address these challenges, this article puts forward a decentralized DRM framework for library systems by leveraging blockchain technology and decentralized DRM-key mechanisms. An integrative review of the available research literature provides an analysis of current blockchain-based DRM library systems, their limitations, and associated challenges. To address these issues, a controlled experiment is set up to implement and evaluate a possible solution. In the proposed model, digital content is encrypted and stored in the Inter-Planetary File System (IPFS), while blockchain smart contracts manage the generation, distribution, and validation of DRM-keys that regulate user-access rights. This approach ensures immutability, transparency, and fine-grained access control without reliance on centralized authorities. Security is enhanced through cryptographic techniques for authentication. The model not only mitigates issues of piracy, unauthorized redistribution, and vendor lock-in, but also provides a scalable and interoperable solution for modern digital libraries. The findings demonstrate how blockchain-enabled DRM-keys can enhance trust, accountability, and efficiency through the development of secure, decentralized, and user-centric digital library systems, which will be of interest to practitioners charged with library IT technology management and to researchers in the wider field of blockchain applications in organizations. Full article

The Linked Autonomous Interplanetary Satellite Orbit Navigation (LiAISON) technique enables cislunar spacecraft to obtain accurate position and velocity information, allowing full state estimation of two vehicles using only inter-satellite range (ISR) measurements when both their dynamical states are unknown. However, its stand-alone use leads to significantly increased orbit determination errors when the orbital planes of the two spacecraft are nearly coplanar, and is characterized by long initial convergence times and slow recovery following dynamical disturbances. To mitigate these issues, this study introduces an integrated navigation method that augments inter-satellite range measurements with line-of-sight vector angles relative to background stars. Additionally, an enhanced Adaptive Robust Cubature Kalman Filter (ARCKF) incorporating a chi-square test-based adaptive forgetting factor (AFF-ARCKF) is developed. This algorithm performs adaptive estimation of both process and measurement noise covariance matrices, improving convergence speed and accuracy while effectively suppressing the influence of measurement outliers. Numerical simulations involving spacecraft in Earth–Moon L4 planar orbits and distant retrograde orbits (DRO) confirm that the proposed method significantly enhances system observability under near-coplanar conditions. Comparative evaluations demonstrate that AFF-ARCKF achieves faster convergence compared to the standard ARCKF. Further analysis examining the effects of initial state errors and varying initial forgetting factors clarifies the operational boundaries and practical applicability of the proposed algorithm. Full article

This study investigates the solar origins of short-term periodicities in the near-Earth solar wind and interplanetary magnetic field (IMF) using long-term observations (1995–2024) and Potential Field Source Surface modeling. We establish that the 27-day periodicity in solar wind speed and its harmonics (13.5-day and 9-day) are governed by the combined influence of polar and low-latitude coronal holes. Polar coronal holes serve as the fundamental stabilizers of the global coronal structure, while the rotation of the Sun in the presence of low-latitude coronal holes acts as the primary mechanism generating periodic fluctuations. The absence of low-latitude coronal holes diminishes or erases these periodicities. For IMF components forming the Parker spiral, the periodicity is controlled by the structure of the heliospheric current sheet (HCS). A stable 27-day period emerges under a two-sector IMF configuration (HCS average slope $\mathrm{SL}>0.4$, latitudinal extent beyond ±30°), while a stable four-sector structure ($\mathrm{SL}>0.6$, latitudinal extent beyond ±60°) superimposes a clear 13.5-day periodicity. However, periodicity weakens or disappears when the HCS is flat and equatorial, or when global structural changes and transient disturbances disrupt recurrence patterns. In contrast, $B_z^{\mathrm{GSE}}$ exhibits weak periodicity due to its transient nature, while $B_z^{\mathrm{GSM}}$ shows intermittent 27-day periodicity modulated by the Russell-McPherron effect. Consequently, geomagnetic indices (Kp, Dst, AE) display periodic behavior similar to $B_z^{\mathrm{GSM}}$, consistent with its crucial role in solar wind-magnetosphere coupling. These results quantitatively link solar surface morphology to heliospheric recurrence, clarifying the conditions under which periodicities emerge or are suppressed throughout the Sun-Earth system. Full article

A sharing framework based on Zero-Knowledge Proof (ZKP) and Proxy Re-encryption (PRE) technologies offers a promising solution for sharing Student Electronic Academic Records (SEARs). As core credentials in the education sector, student records are characterized by strong identity binding, the need for long-term retention, frequent cross-institutional verification, and sensitive information. Compared with electronic health records and government archives, they face more complex security, privacy protection, and storage scalability challenges during sharing. These records not only contain sensitive data such as personal identity and academic performance but also serve as crucial evidence in key scenarios such as further education, employment, and professional title evaluation. Leakage or tampering could have irreversible impacts on a student’s career development. Furthermore, traditional blockchain technology faces storage capacity limitations when storing massive academic records, and existing general electronic record sharing solutions struggle to meet the high-frequency verification demands of educational authorities, universities, and employers for academic data. This study proposes a dedicated sharing framework for students’ electronic academic records, leveraging PRE technology and the distributed ledger characteristics of blockchain to ensure transparency and immutability during sharing. By integrating the InterPlanetary File System (IPFS) with Ethereum Smart Contract (SC), it addresses blockchain storage bottlenecks, enabling secure storage and efficient sharing of academic records. Relying on optimized ZKP technology, it supports verifying the authenticity and integrity of records without revealing sensitive content. Furthermore, the introduction of gate circuit merging, constant folding techniques, Field-Programmable Gate Array (FPGA) hardware acceleration, and the efficient Bulletproofs algorithm alleviates the high computational complexity of ZKP, significantly reducing proof generation time. The experimental results demonstrate that the framework, while ensuring strong privacy protection, can meet the cross-scenario sharing needs of student records and significantly improve sharing efficiency and security. Therefore, this method exhibits superior security and performance in privacy-preserving scenarios. This framework can be applied to scenarios such as cross-institutional academic certification, employer background checks, and long-term management of academic records by educational authorities, providing secure and efficient technical support for the sharing of electronic academic credentials in the digital education ecosystem. Full article

Aerodynamic manoeuvring technology for spacecraft actively utilizes aerodynamic forces to alter orbital trajectories. This approach not only substantially reduces propellant consumption but also expands the range of accessible orbits, representing a key technological pathway to address the demands of increasingly complex yet cost-effective space missions. The theoretical prototype of this technology was proposed by Howard London. Over the course of more than half a century of development, it has evolved into four distinct modes: aeroglide, aerocruise, aerobang, and aerogravity assist. These modes have been engineered and applied in scenarios such as in-orbit manoeuvring of reusable vehicles, rapid response to space missions, and interplanetary exploration. Our research centers on two core domains: trajectory optimization and control guidance. Trajectory optimization employs numerical methods such as pseudo-spectral techniques and sequential convex optimization to achieve multi-objective optimization of fuel and time under constraints, including heat flux and overload. Control guidance focuses on standard orbital guidance and predictive correction guidance, progressively evolving into adaptive and robust control to address atmospheric uncertainties and the challenges of strong nonlinear coupling. Although breakthroughs have been achieved in deep-space exploration missions, critical challenges remain, including constructing high-fidelity models, enhancing real-time computational efficiency, ensuring the explainability of artificial intelligence methods, and designing integrated framework architectures. As these technical hurdles are progressively overcome, this technology will find broader engineering applications in diverse space missions such as lunar return and in-orbit servicing, driving continuous innovation in the field of space dynamics and control. Full article

Multi-revolution Lambert solvers are intended to find the elliptic transfer orbits that are traveled multiple times and connect two specified positions in prescribed time, under the assumption of considering natural (Keplerian) orbital motion in the presence of a single attracting body. This study proposes and tests a new, effective multi-revolution Lambert solver that employs the initial true anomaly, which identifies the initial position along the transfer ellipse, as the unknown variable. The related search interval is identified through closed-form expressions for upper and lower bounds. A simple numerical algorithm is developed and employed over the entire search interval to detect all Lambert solutions. The new multi-revolution solver proposed in this work is simple to understand and easy to implement and is successfully tested in several challenging scenarios (corresponding to some pathological cases reported in the recent scientific literature), as well as for the study of Earth–Mars interplanetary transfers. Comparison with alternative, up-to-date techniques points out that the new approach at hand is able to detect all the feasible transfer ellipses, in all cases, with very satisfactory accuracy in terms of final position error, even in challenging scenarios that include a huge number of revolutions or near-antipodal terminal positions. Full article

Electric propulsion (EP) has become a pivotal technology in modern space exploration, enabling prolonged mission durations, increased payload capacity, and precise deep-space navigation through its superior thrust efficiency and low propellant consumption. However, the performance of EP systems is fundamentally limited by the power processing unit (PPU), with the DC-DC power converter serving as the core of the PPU. Existing research on DC-DC converters often focuses on generic topologies, failing to address the divergent power demands of distinct EP types and the harsh space-specific constraints. This review aims to fill this gap by systematically analyzing DC-DC power converters tailored for EP systems. First, the core requirements of converters across major EP categories are classified. Then, converter topologies are compared by evaluating the suitability for EP operational and space constraints. Moreover, high step-up conversion techniques are explored that bridge the gap between low-voltage spacecraft buses and thruster power needs. Furthermore, this review highlights emerging technologies driving EP converter advancement, such as wide-bandgap semiconductors for improved power density and efficiency, planar magnetics for miniaturization, and direct-drive architecture for simplified Hall-effect thruster integration. It also identifies unresolved challenges, including balancing power density with thermal robustness, mitigating radiation-induced degradation, and suppressing electromagnetic interference (EMI). Finally, it outlines future research directions, such as optimizing WBG-compatible converter topologies, developing advanced thermal management solutions, and standardizing EP-specific design guidelines. This work provides a practical reference for PPU engineers, linking converter design to EP unique demands and space constraints while guiding innovations to advance EP technology for next-generation space missions, from low-Earth orbit satellites to interplanetary exploration. Full article

This study presents a novel framework for digital copyright management that integrates AI-enhanced perceptual hashing, blockchain technology, and digital watermarking to address critical challenges in content protection and verification. Traditional watermarking approaches typically employ content-independent metadata and rely on centralized authorities, introducing risks of tampering and operational inefficiencies. The proposed system utilizes a pre-trained convolutional neural network (CNN) to generate a robust, content-based perceptual hash value, which serves as an unforgeable watermark intrinsically linked to the image content. This hash is embedded as a QR code in the frequency domain and registered on a blockchain, ensuring tamper-proof timestamping and comprehensive traceability. The blockchain infrastructure further enables verification of multiple watermark sequences, thereby clarifying authorship attribution and modification history. Experimental results demonstrate high robustness against common image modifications, strong discriminative capabilities, and effective watermark recovery, supported by decentralized storage via the InterPlanetary File System (IPFS). The framework provides a transparent, secure, and efficient solution for digital rights management, with potential future enhancements including post-quantum cryptography integration. Full article

For millennia, theologians and philosophers debated whether extraterrestrial intelligent life (ETI) exists in the universe. Some theologians concluded God enjoys creating so much he would not stop at one planet. Others argue God limits his miracles to those needed to achieve his purposes, which require only one planet with intelligent life. Thanks to exponential advances in observational astrophysics, scientists now are weighing in on the “are we alone in the cosmos” debate. Though far from resolving all the debate’s components, they now are able to provide definitive answers or steps towards definitive answers to several of the theological/philosophical issues. These answers arise from the following research endeavors: (1) search for ETI (SETI) efforts, results, and determined odds; (2) interplanetary panspermia; (3) ETI planetary habitability requirements; (4) ETI stellar habitability requirements; (5) ETI galactic habitability requirements; (6) “hard steps” in the evolution of life from non-life; (7); “hard steps” in ETI evolution from simple life; (8) interstellar space travel and exploration limitations; (9) nature of UAPs lacking natural or human-made explanations; and (10) nature of non-physical reality. The resultant answers increasingly are creating arenas of common agreement plus opening up avenues of dialog among theologians and scientists. This dialog on ‘are we alone in the cosmos’ is shedding additional light on humanity’s role and purposes in the cosmos. Full article

This review presents an in-depth exploration of trajectory optimization techniques for various orbit transfer applications, focusing on principles, methodologies, and practical case studies. The emphasis is placed on indirect, direct, and data-driven trajectory optimization methods powered by numerical, deterministic, and gradient-based optimization algorithms, and an overview on the basic fundamentals of each method is provided. Applications cover numerous orbit transfer problems, from geocentric and interplanetary transfers to other orbital maneuvers that are applicable to the orbit transfer problem, highlighting critical advancements of trajectory optimization techniques in enabling more efficient and feasible space missions. A minimum-fuel transfer from Earth to Mars is considered as a case study and solved using the indirect, direct, and data-driven methods, respectively, demonstrating an effective primer on the implementation of each method. Finally, we identify open challenges and issues, discuss potential opportunities, and make suggestions for future research directions. By synthesizing current methods and emerging trends, this review provides a comprehensive toolkit for addressing complex challenges in orbit transfers. Full article

Recent space exploration roadmaps from China, the United States, and Russia highlight the establishment of Mars bases as a major objective. Future deep-space missions will span the inner solar system and extend beyond the asteroid belt, demanding network control systems that sustain reliable communication and efficient scheduling across vast distances. Current centralized or regionalized technologies, such as the Deep-Space Network and planetary relay constellations, are limited by long delays, sparse visibility, and heterogeneous onboard resources, and thus cannot meet these demands. To address these challenges, we propose a dual-center architecture, DualSynNet, anchored at Earth and Mars and enhanced by Lagrange-point relays and a minimal heliocentric constellation to provide scalable multi-mission coverage. On this basis, we develop a federated multi-agent reinforcement learning framework with graph attention (Fed-GAT-MADDPG), integrating centralized critics, decentralized actors, and interplanetary parameter synchronization for adaptive, resource-aware scheduling. A unified metric system: Reachability, Rapidity, and Availability, is introduced to evaluate connectivity, latency, and resource sustainability. Simulation results demonstrate that our method increases task completion to 52.4%, reduces deadline expiration, constrains rover low-state-of-charge exposure to approximately 0.8%, and maintains consistently high hardware reliability across rover and satellite nodes. End-to-end latency is reduced, with a shorter tail distribution due to fewer prolonged buffering or stagnation periods. Ablation studies confirm the essential role of graph attention, as removing it reduces completion and raises expiration. These results indicate that the integration of a dual-center architecture with federated graph reinforcement learning yields a robust, scalable, and resource-efficient framework suitable for next-generation interplanetary exploration. Full article

The aim of this study was to find out whether, just like in March 2015, daily regular GPS positioning disturbances caused by ionospheric scintillations occurred in other months of the solar activity cycle 24. The GPS positioning 90-s kinematic solutions of selected 46 months covering 11 years were used to search for regular daily scintillation events. The hypothesis on predictable regular daily ionospheric scintillation was tested. Scintillation waves were discovered as a result of space weather impact with the sidereal day regularity. It leads to the conclusion that the radiation originates from the interplanetary medium. The enhancement of radiation waves by solar activity is similar to Pc1 waves. The regular daily ionospheric scintillation waves are recorded at any time of the day. In the years with low solar activity in 2010 and 2012, regular scintillation waves were not found. It cannot be claimed that the comparison of daily regular ionospheric scintillation cases over time with the mentioned Pc1 wave cases indicates any interrelation. Full article

Pleurotus ostreatus is valued for its nutritional, medicinal, economic, and ecological benefits and is widely used in the food, pharmaceutical, and environmental protection industries. Pleurotus ostreatus, as a highly perishable edible fungus, faces significant challenges in supply chain quality control and food safety due to its short shelf life. As consumer demand for food freshness and full traceability increases, there is an urgent need to establish a reliable traceability system that enables real-time monitoring, spoilage prevention, and quality assurance. This study focuses on the Pleurotus ostreatus supply chain and designs and implements a multi-role flexible traceability system that integrates blockchain and the Internet of Things. The system collects key production and storage environment parameters in real time through sensor networks and enhances data accuracy and robustness using an improved adaptive weighted fusion algorithm, enabling precise monitoring of the growth environment and quality risks. The system adopts a “link-chain” mapping mechanism for multi-chain storage and dynamic reorganization of business processes. It incorporates attribute-based encryption strategies and smart contracts to support tiered data access and secure sharing among multiple parties. Key information is stored on the blockchain to prevent tampering, while auxiliary data is stored in off-chain databases and the Interplanetary File System to ensure efficient and verifiable data queries. Deployed at Shandong Qihe Ecological Agriculture Co., Ltd., No. 517, Xilou Village, Kunlun Town, Zichuan District, 255000, Zibo City, Shandong Province, China, the system covers 12 cultivation units and 60 sensor nodes, recording over 50,000 traceable data points. Experimental results demonstrate that the system outperforms baseline methods in query latency, data consistency, and environmental monitoring accuracy. The improved fusion algorithm reduced the total variance of environmental data by 20%. In practical application, the system reduced the spoilage rate of Pleurotus ostreatus by approximately 12.3% and increased the quality inspection pass rate by approximately 15.4%, significantly enhancing the supply chain’s quality control and food safety capabilities. The results show that the framework is feasible and scalable in terms of information credibility and operational efficiency and significantly improves food quality and safety monitoring throughout the production, storage, and distribution of Pleurotus ostreatus. This study provides a viable technological path for spoilage prevention, quality tracking, and digital food safety supervision, offering valuable insights for both food science research and practical applications. Full article

The growing body of biomedical research reveals that many biological processes are governed by quantum physical principles, including the effects of weak magnetic fields (MFs) at or below geomagnetic strength. Given that life evolved within the geomagnetic field, its significant decrease—the hypomagnetic field (hypoMF)—may disrupt fundamental biological processes. This is particularly relevant for interplanetary missions, where astronauts will encounter prolonged hypoMF conditions alongside other spaceflight stressors. This mini-review synthesizes current knowledge on hypoMF effects, comparing terrestrial and extraterrestrial MF conditions and evaluating evidence from human studies. The initial database search identified 645 records. After most were excluded for various reasons, only 44 publications on the effects of MFs on the entire human body were included in the review. An effect of the hypoMF was reported in 10 of these studies and was absent in 4. Despite some methodological limitations in the available research, the evidence suggests that the human body is not indifferent to hypoMF exposure. We also discuss leading mechanistic molecular hypotheses—particularly the radical pair mechanism. Finally, we identify urgent research priorities to elucidate hypoMF’s biological role and develop countermeasures for future deep space exploration. Addressing these gaps is essential for safeguarding astronaut health and advancing magnetobiology as a frontier discipline in biophysics. Full article