Network Science and Graph Analytics

SpaceX Falcon 9 deploys 21 satellites for US military’s secure communication network SpaceX successfully launched 21 satellites on September 10 (2025), from the Vandenberg Space Force Base, California. The satellites are sent to the low Earth orbit (LEO), and this has marked the start of the US military’s new encrypted space-based communications network, which is led by the Space Development Agency (SDA). The mission was the first Tranche-1 Transport Layer launch, which will eventually form a constellation of 126 satellites. The Falcon 9’s first stage completed its sixth flight and safely landed on the SpaceX droneship in the Pacific Ocean about 8.5 minutes after liftoff. Payload and Contractors The payload consisted of 21 satellites manufactured by York Space Systems. To complete the Tranche-1 constellation, Lockheed Martin and Northrop Grumman have also been contracted, each tasked with building 42 satellites. While SpaceX confirmed the deployment into orbit, the exact timin...

Modular Soft Sensor Made of Eutectogel and Its Application in Gesture Recognition Soft sensors are designed to be flexible, making them ideal for wearable devices as they can conform to the human body during motion, capturing pertinent information effectively. However, once these wearable sensors are constructed, modifying them is not straightforward without undergoing a re-prototyping process. In this study, we introduced a novel design for a modular soft sensor unit (M2SU) that incorporates a short, wire-shaped sensory structure made of eutectogel, with magnetic blocks at both ends. This design facilitates the easy assembly and reversible integration of the sensor directly onto a wearable device in situ. Leveraging the piezoresistive properties of eutectogel and the dual conductive and magnetic characteristics of neodymium magnets, our sensor unit acts as both a sensing element and a modular component. To explore the practical application of M2SUs in wearable sensing, we equipped a g...

Double-Sided Conformable Piezoelectric Force Sensor with Enhanced Performance and Bending Correction Flexible piezoelectric devices have gained considerable interest due to their potential for new applications, particularly in wearable technology. However, a significant challenge remains in measuring low forces on nonplanar and deformable surfaces. Indeed, conformability on complex surfaces induces bending stresses in the piezoelectric sensors, interfering with the measurement of compressive force. Yet such measurements can be valuable, especially in medical applications that involve assessing forces on soft tissues. This study presents an innovative highly sensitive conformable sensor based on a thin film of P (VDF-TrFE) copolymer. The selection of the substrate is essential for ensuring the device's conformability, but it is also demonstrated that it can provide a substantial improvement in performance if its Young's modulus is lower than that of the active polymer. The effe...

Discrete Hartley transform - orthogonal frequency division multiplexing underwater acoustic communication system based on complex-to-real conversion In this paper, we propose a Complex-to-Real Transformation (C2RT) for Discrete Hartley Transform Orthogonal Frequency Division Multiplexing (DHT-OFDM) in underwater acoustic communication system. C2RT is an efficient system modulation scheme based on the principle of index modulation. Traditional DHT-OFDM systems only support modulation and demodulation in the real domain, which limits the use of high-order phase modulation.   This restriction makes it difficult to improve communication rates and bandwidth utilization. C2RT is an effective solution to this problem. By incorporating this algorithm into DHT-OFDM system, high-order phase modulation can be achieved while maintaining the system's real-valued characteristics. Additionally, due to the sparsity of its output sequence, C2RT provides higher transmission accuracy compared to dir...

Performance Impact of Wind Speed on MAC Protocols for Underwater Wireless Sensor Networks Acoustic communication in under water environments is challenging due to high propagation delay and severely limited bandwidth. Furthermore, the quality of the channel is dynamically changing due to wind, rain, temperature and other environmental factors. Efficient medium access control (MAC) protocols are therefore particularly important for acoustic sensor networks ( UWSNs ) to prevent a significant portion of the scarce bandwidth to be wasted on packet collision. Increased wind speed add surface roughness for underwater communication, which in turn can affect the overall performance of MAC protocols in UWSNs. The contribution of this paper is to investigate the performance of five MAC protocols for UWSNs in terms of packet delivery rate, energy consumption and delay under different wind speeds. The protocols investigated are: Aloha, Aloha with carrier sense (Aloha-CS), Carrier Sense Multiple Ac...

One-dimensional C/Co composite nanofibers derived from ZIF-67 with excellent wideband electromagnetic microwave absorption performance The rapid advancement of wireless communications, radar systems, and electronic devices has resulted in a substantial increase in electromagnetic interference (EMI), which poses a threat to electronic device performance and human health. This study addresses the urgent need for lightweight materials with strong absorption capacities, wide absorption bandwidths, and low thickness values. For this purpose, ZIF-67-derived C/Co nanofibers were synthesized via electrospinning, dipping, and high-temperature carbonization . Co2+ ions were pre-anchored and encapsulated in polyacrylonitrile (PAN) fibers and are grown by immersion in an organic ligand. Utilizing 0.4 g of cobalt nitrate hexahydrate, the amount of encapsulated Co2+ was optimized to provide the greatest electromagnetic wave absorption performance. Under these conditions, the reflection loss was −4...

3D printed and circularly polarized 28 GHz patch antenna array for small satellite communications This paper presents the design, fabrication, and testing of a high-gain compact 2 × 2 circularly polarized patch antenna array using 3D printing technology for small satellite 5G communication at 28 GHz. The proposed antenna demonstrates high efficiency and a low profile, addressing the limitations in design flexibility associated with traditional PCB fabrication methods . The 2 × 2 array configuration, incorporating via fences, coaxial vertical feedlines, and a sequentially rotated phased feed network, enhances the antenna's bandwidth and axial ratio bandwidth while maintaining compactness, crucial for space-constrained satellite applications. Simulations optimized key antenna parameters, including reflection coefficient , gain, and axial ratio. Measurement results validated the simulations, showing an impedance bandwidth of 6.8 GHz and an axial ratio bandwidth of 3.1 GHz, with a ...

Multi-Radar Track Fusion Method Based on Parallel Track Fusion Model With the development of multi-sensor collaborative detection technology, radar track fusion has become a key means to improve target tracking accuracy. Traditional fusion methods based on Kalman filtering and weighted averaging have the problem of insufficient adaptability in complex environments. This paper proposes an end-to-end deep learning track fusion method, which achieves high-precision track reconstruction through residual extraction and parallel network fusion, providing a new end-to-end method for track fusion. The method combines the attention mechanism and the long short-term memory network in parallel and optimizes the computational complexity. Through the uncertainty weighting mechanism, the fusion weight is dynamically adjusted according to the reliability of the track features. Experimental results show that the mean absolute error of fusion accuracy of this method is 79% lower than the Kalman filter ...