This paper proposes a novel data acquisition framework in sensor networks using an unmanned aerial vehicle (UAV) with the goal of increasing the efficiency of the data gathering efforts. To maximize the system throughput, we introduce a priority-based frame selection scheme to suppress the number of redundant data transmissions between sensor nodes and the UAV. Toward this goal, we classify the nodes inside the UAV's coverage area into different frames according to their locations. Taking advantage of the mobility of the UAV, we assign different transmission priorities to nodes in different frames. To do that, we introduce an adjustment to the contention window value used in IEEE 802.11 MAC, thereby defining a lower contention window range to the frame with higher priority (urgent area) and a higher contention window range to the frame with lower priority (less important area). The proposed framework leads to a reduction in packet collisions and, at the same time, minimizes the packet loss originated from nodes in the rear-side of the UAV when the UAV moves in the forward direction. To optimize the networks' energy consumption, we present a novel routing protocol based on the aforementioned framework. By leveraging the proposed framework and routing algorithm, we aim to reduce the transmission distances between senders and receivers. A shorter distance leads to better channel quality and energy savings, as is verified by our simulation studies and results.

Chemical compounds dissolved in insulating oil, as indicators can excellently monitor the paper aging condition, which has attracted increasing interest in areas of transformer condition monitoring and fault diagnosis. Because of their outstanding features, such as good correlation with the degree of polymerization of cellulose paper and the aid of non-destructive online monitoring, chemical indicators have been effectively used for transformer condition assessment. In this study, a comprehensive, in-depth insight into the indicators of the aging of insulating paper from aging characteristics, physico-chemical characteristics, shortcomings of various compounds, generation pathways and mechanisms, and monitoring technologies are provided. It is expected that these chemical indicators can provide better guidance for the evaluation of paper insulation performance and transformer aging. In addition, the latest research progress, as well as current challenges and future prospects are also outlined. This study provides a theoretical basis and reference for chemical indicators in the fields of microscopic formation mechanism, diffusion equilibrium phenomenon, and insulation aging state assessment.

In this paper, we propose a sensor-based data acquisition glove for Japanese Sign Language (JSL) hand gesture recognition. Five flex sensors, an Inertial Measurement Unit (IMU), and three Force Sensing Resistors (FSRs) are used to detect the bending degree of fingers and hand movement information. The detected data are transmitted to the computer by an Arduino Micro. The average accuracy of the hand gesture recognition for a single subject, using the Support Vector Machine (SVM) based and the Dynamic Time Wrapping (DTW) based algorithm are 96.9% and 94.5%, respectively. Our proposed system also achieves an average recognition accuracy of about 82.5% for the cross-recognition among three subjects. The experimental results indicate that our proposed system has great potential for JSL hand gesture recognition.

This article proposes a novel chunk-based caching scheme known as the Progressive Popularity-Aware Caching Scheme (PPCS) to improve content availability and eliminate the cache redundancy issue of Information-Centric Networking (ICN). Particularly, the proposal considers both entire-object caching and partial-progressive caching for popular and non-popular content objects, respectively. In the case that the content is not popular enough, PPCS first caches initial chunks of the content at the edge node and then progressively continues caching subsequent chunks at upstream Content Nodes (CNs) along the delivery path over time, according to the content popularity and each CN position. Therefore, PPCS efficiently avoids wasting cache space for storing on-path content duplicates and improves cache diversity by allowing no more than one replica of a specified content to be cached. To enable a complete ICN caching solution for communication networks, we also propose an autonomous replacement policy to optimize the cache utilization by maximizing the utility of each CN from caching content items. By simulation, we show that PPCS, utilizing edge-computing for the joint optimization of caching decision and replacement policies, considerably outperforms relevant existing ICN caching strategies in terms of latency (number of hops), cache redundancy, and content availability (hit rate), especially when the CN’s cache size is small.

A radio frequency memory (RFM) based on microwave photonic mixing and digital RFM is proposed and demonstrated. By introducing the microwave photonic mixing, the operational frequency range is largely extended. Besides, the mixing spurs are effectively suppressed, which is important to guarantee the system efficiency and avoid generating significant feature for the jamming recognition. Meanwhile, by applying the digital RFM, flexible modulation and reconstruction are achieved. A proof-of-concept experiment is carried out. The wide working frequency range from C- to Ka- bands is achieved. The mixing spurs over the 0–40 GHz frequency range are experimentally suppressed. Radar imaging is successfully deceived. A radar waveform with a bandwidth of 500 MHz in the K band is successfully received and reconstructed. Two false targets are added. To the best of our knowledge, it is the first time that a photonics-assisted RFM is reported to have the functions of storage, flexible modulation, and reconstruction with wideband RF signals at a high frequency. The proposed scheme shows the great potential to be applied in electronic warfare, electronic environment simulation and testing, and so on.