Search Results (6,116)

Lithium-ion batteries (LIBs) are widely used as energy storage units in electric vehicles, mobile phones, and other electric devices due to their high voltage, large capacity, and long cycle life. Lithium-ion batteries are prone to thermal runway (TR), resulting in fires and explosions, which can seriously hinder the commercial development of LIBs. A series of safety methods has been studied to prevent TR of LIBs. The safety methods for suppressing TR in LIBs were reviewed, including safety equipment method, material modification method, thermal management method, and cooling method. The mechanism, advantages and disadvantages, and future applications of the TR suppression method are discussed. The effectiveness of the proposed safety method was evaluated through technical analysis and experimental testing, and the inhibitory effects of different safety methods on battery TR were summarized. The future trend of suppressing TR is discussed by summarizing and generalizing existing technologies for suppressing thermal runaway. This study provides a reference for exploring more effective methods to mitigate TR in the future. Full article

In the first part of this study, Y₂O₃-doped copper thiocyanate (CuSCN) with different x wt% (named CuSCN-xY, x = 0, 1, 2, and 3) films were synthesized onto ITO substrates using the spin coating method. UV-vis, SEM, AFM, EDS, and cyclic voltammetry were used to investigate the material properties of the proposed films. The conductivity and carrier mobility of the films increased with additional yttrium doping. It was found that the films with 2% Y₂O₃ (CuSCN-2Y) have the smallest valence band edges (5.28 eV). Meanwhile, CuSCN-2Y films demonstrated the densest surface morphology and the smallest surface roughness (22.8 nm), along with the highest conductivity value of 764 S cm⁻¹. Then, P-I-N self-powered UV photodetectors (PDs) were fabricated using the ITO substrate/ZnO seed layer/ZnO nanorod/CsPbBr₃/CuSCN-xY/Ag structure, and the characteristics of the devices were measured. In terms of response time, the rise time and fall time were reduced from 26 ms/22 ms to 9 ms/5 ms; the responsivity was increased from 243 mA/W to 534 mA/W, and the on/off ratio was increased to 2.47 × 10⁶. The results showed that Y₂O₃ doping also helped improve the P-I-N photodetector’s device performance, and the mechanisms were investigated. Compared with other published P-I-N self-powered photodetectors, our proposed devices show a fairly high on/off ratio, quick response times, and high responsivity and detectivity. Full article

With the growing concern for environmental issues, progress has been made recently in the promotion of new technologies in the field of renewable energies. This article studies a new wave energy converter that uses the heel generated by the mechanical energy of the waves to transform it into electrical energy by means of a mobile mass, coupled to an electrical generator, which moves from port to starboard and vice versa. The advantage of this converter is that it is capable of incorporating the energy conversion unit inside the converter, as well as allowing the placement of a set of several devices within the same collector, and of modifying the roll period to adapt it to the wave conditions of the installation area. To do this, on one side, two models of wave energy converters were compared by varying the beam to check whether it is better to have a smaller or larger beam by carrying out roll decay tests and simulations for different waves. Moreover, the maximum power available in the moving mass of the power take-off was calculated theoretically for two situations of different transverse metacentric height to check which is more efficient, reaching 2 MW for some waves. Full article

The rise of the Internet of Things (IoT) has made it possible to explore different types of communication, such as underwater IoT (UIoT). This new paradigm allows the interconnection of ships, boats, coasts, objects in the sea, cameras, and animals that require constant monitoring. The use of sensors for environmental monitoring, tracking marine fauna and flora, and monitoring the health of aquifers requires the integration of heterogeneous technologies as well as wireless communication technologies. Aquatic mobile sensor nodes face various limitations, such as bandwidth, propagation distance, and data transmission delay issues. Owing to their versatility, wireless sensor networks support remote monitoring and surveillance. In this work, an architecture for a general packet radio service (GPRS) wireless sensor network is presented. The network is used to monitor the geographic position over the coastal area of the Gulf of Mexico. The proposed architecture integrates cellular technology and some ad hoc network configurations in a single device such that coverage is improved without significantly affecting the energy consumption, as shown in the results. The network coverage and energy consumption are evaluated by analyzing the attenuation in a proposed channel model and the autonomy of the electronic system, respectively. Full article

This work presents the experimental evaluation of a robotic walker following the full implementation of its sensor and motorization system. The aging population and increasing mobility impairments drive the need for assistive robotic technologies that enhance safe and independent movement. The main objective was to validate the device’s behavior in real-use scenarios by assessing its stability, responsiveness, and accuracy in detecting user movement. Tests were carried out in straight-line walking and on paths involving directional changes, both with and without motor assistance, using a cohort of five test users. Principal Component Analysis (PCA) and t-SNE dimensionality reduction techniques were applied to analyze the inertial (IMU) and proximity (TOF) sensor data, complemented by motor control monitoring through wheel Hall sensors, to explore gait patterns and system performance. Additionally, synchronized measurements between the user’s and walker’s inertial units and Time-of-Flight sensors allowed the evaluation of spatial alignment and motion correlation. The results provide a foundation for future system adjustment and optimization, ensuring the walker offers effective, safe, and adaptive assistance tailored to the user’s needs. Findings reveal that the walker successfully distinguishes individual gait patterns and adapts its behavior accordingly, demonstrating its potential for personalized mobility support. Full article

The integration of Unmanned Aerial Vehicles (UAVs) into Mobile Edge Computing (MEC) systems has emerged as a transformative solution for latency-sensitive applications, leveraging UAVs’ unique advantages in mobility, flexible deployment, and on-demand service provisioning. This paper proposes a novel multi-agent reinforcement learning framework, termed Multi-Agent Twin Delayed Deep Deterministic Policy Gradient for Task Offloading and Resource Allocation (MATD3-TORA), to optimize task offloading and resource allocation in UAV-assisted MEC networks. The framework enables collaborative decision making among multiple UAVs to efficiently serve sparsely distributed ground mobile devices (MDs) and establish an integrated mobility, communication, and computational offloading model, which formulates a joint optimization problem aimed at minimizing the weighted sum of task processing latency and UAV energy consumption. Extensive experiments demonstrate that the algorithm achieves improvements in system latency and energy efficiency compared to conventional approaches. The results highlight MATD3-TORA’s effectiveness in addressing UAV-MEC challenges, including mobility–energy tradeoffs, distributed decision making, and real-time resource allocation. Full article

Background/Objectives: Hearing aids are essential for managing hearing loss, yet their accessibility, consistent use, and maintenance remain challenging in public healthcare systems, particularly in low- and middle-income countries (LMICs) such as South Africa. Despite the availability of these services, many patients struggle with device utilization, resulting in suboptimal rehabilitation outcomes. This study explores patient experiences with hearing aids in South Africa’s public healthcare sector. This study aimed to (1) assess patients’ experiences with hearing aid access, including waiting times and service delivery; (2) identify challenges related to hearing aid maintenance and repairs in the public sector; (3) explore factors influencing consistent hearing aid use, including social, psychological, and practical barriers; and (4) propose strategies to enhance hearing aid provision and aftercare services in South Africa. Methods: This descriptive qualitative study was conducted at two public healthcare facilities in Johannesburg. Purposive sampling was used to recruit 15 adult hearing aid users who had received government-funded hearing aids within the past 12 months. Semi-structured interviews were conducted, transcribed verbatim, and analyzed using thematic analysis. Results: Participants reported long waiting periods (up to a year) for hearing aids, with poor communication regarding timelines. Challenges included difficulties adjusting to amplification, discomfort, and battery shortages, leading to inconsistent use or device abandonment. Social stigma and lack of family support further discouraged consistent use. Repair services were slow, with waiting times exceeding three months. Participants recommended decentralized battery distribution, structured follow-up appointments, improved aftercare, awareness campaigns, and mobile audiology services to improve accessibility and usability. Conclusions: While public hearing aid provision is essential for hearing rehabilitation, systemic inefficiencies, maintenance issues, and social barriers limit its impact. Strengthening aftercare services, decentralizing hearing aid distribution, and increasing public awareness could significantly improve hearing aid accessibility and adherence. Furthermore, policy interventions that incorporate tele-audiology, community-based maintenance programs, and integrated healthcare approaches are crucial in ensuring sustainable hearing healthcare outcomes. Full article

Background: Hallux rigidus is a painful and degenerative pathology of the first metatarsophalangeal (MTP1) joint. In severe cases it is usually appropriate to consider arthrodesis or arthroplasty of the joint. Arthrodesis represents the gold standard, but arthroplasty allows patients to recover mobility. Although arthroplasty has slightly inferior functional results to arthrodesis, it has shown very good results in terms of joint mobility, patient satisfaction and pain reduction. The goal of the present study was to evaluate short-term outcomes of patients that received a third-generation double-stemmed MTP1 implant manufactured from high-performance silicon. Methods: In this retrospective study the authors analyzed data of 37 patients who underwent MPT1 joint arthroplasty with Silktoe^TM double-stemmed implant using the R 4.2.2 software (R Foundation for Statistical Computing, Vienna, Austria). The indications were hallux rigidus of grade III and grade IV (81.1%), hallux rigidus plus valgus (10.8%), painful or unstable joint following previous surgery (5.4%) and hallux rigidus due to gout (2.7%). Data were collected during routine visits at 1 and 6 months and 1 and 2 years. Results: There were no intraoperative and postoperative complications. There were no revisions or reoperations at a follow-up of two years. The American Orthopaedic Foot and Ankle Society-Hallux Metatarsophalangeal-Interphalangeal Scale (AOFAS-HMI) score was 94.6 ± 7.6 (median, 100; range, 70–100) and the Visual Analogue Scale (VAS) score was 0.4 ± 0.80 (median, 0; range, 0–3.5) at the final follow-up. Conclusions: The data from this study presented excellent short-term results for patients who received an arthroplasty of the MTP1 joint using a third-generation double-stemmed spacer made of high-performance silicone. For all patients who received the Silktoe^TM implant, AOFAS-HMI scores of 94.6 and VAS scores of 0.4 were obtained at a two-year follow-up. These values were in line with results reported in the literature for similar devices. Full article

Background/Objectives: The stability of dual mobility (DM) total hip arthroplasty (THA) is often attributed to reduced impingement incidence and a superior range of motion (ROM) compared to the corresponding values when standard implants are used. However, few studies have directly explored this. Thus, the purpose of the present study was to compare the incidence of impingement and the range of motion between standard and DM acetabular cups, whose diameters are suited to the same patient anatomy. Methods: One standard and two DM implants were virtually implanted into a pelvis using a previously developed geometric model. Joint motions, which were representative of seven dislocation-prone activities of daily living (ADLs), as well as walking, were applied to each device type at a range of cup orientations (inclination/anteversion). Conclusions: There were no placement positions that avoided impingement across all seven ADLs, regardless of cup construct type. A similar impingement incidence and ROM were observed for standard and DM constructs, although the consequences of impingement are potentially more serious for DM devices (metal–metal contact) than for standard constructs (metal–polyethylene contact). This finding contradicts the common notion that DM-THAs have a reduced impingement incidence and superior ROM, instead suggesting that their stability may be attributed to alternative mechanisms, such as increased jump distance. Full article

This paper presents an intelligent navigation wearable device for visually impaired individuals. The system aims to improve their independent travel capabilities and reduce the negative emotional impacts associated with visible disability indicators in travel tools. It employs an RGB-D camera and an inertial measurement unit (IMU) sensor to facilitate real-time obstacle detection and recognition via advanced point cloud processing and YOLO-based target recognition techniques. An integrated intelligent interaction module identifies the core obstacle from the detected obstacles and translates this information into multidimensional auxiliary guidance. Users receive haptic feedback to navigate obstacles, indicating directional turns and distances, while auditory prompts convey the identity and distance of obstacles, enhancing spatial awareness. The intuitive vibrational guidance significantly enhances safety during obstacle avoidance, and the voice instructions promote a better understanding of the surrounding environment. The device adopts an arm-mounted design, departing from the traditional cane structure that reinforces disability labeling and social stigma. This lightweight mechanical design prioritizes user comfort and mobility, making it more user-friendly than traditional stick-type aids. Experimental results demonstrate that this system outperforms traditional white canes and ultrasonic devices in reducing collision rates, particularly for mid-air obstacles, thereby significantly improving safety in dynamic environments. Furthermore, the system’s ability to vocalize obstacle identities and distances in advance enhances spatial perception and interaction with the environment. By eliminating the cane structure, this innovative wearable design effectively minimizes social stigma, empowering visually impaired individuals to travel independently with increased confidence, ultimately contributing to an improved quality of life. Full article

It is critical to solidify surveillance in 3D environments with heterogeneous sensors. This study introduces an innovative deep learning-assisted surveillance reinforcement system with smart sensors for resource-constrained cyber-physical devices and mobile elements. The proposed system incorporates deep learning technologies to address the challenges of dynamic public environments. By enhancing the adaptability and effectiveness of surveillance in environments with high human mobility, this paper aims to optimize surveillance node placement and ensure real-time system responsiveness. The integration of deep learning not only improves accuracy and efficiency but also introduces unprecedented flexibility in surveillance operations. Full article

Sonar images possess characteristics such as low resolution, high noise, and blurred edges. Utilizing CNNs would lead to problems such as inadequate target recognition accuracy. Moreover, due to their larger sizes and higher computational requirements, existing CNNs face deployment issues in embedded devices. Therefore, we propose a sonar image recognition algorithm optimized for the lightweight algorithm, MobileViT, by analyzing the features of sonar images. Firstly, the MobileViT block is modified by adding and redesigning the jump connection layer to capture more important features of sonar images. Secondly, the original 1 × 1 convolution is replaced with the redesigned multi-scale convolution Res2Net in the MV2 module to enhance the ability of the algorithm to learn global and local features. Finally, the IB loss is applied to address the imbalance of sample categories in the sonar dataset, assigning different weights to the samples to improve the performance of the network. The experimental results show that several proposed improvements have improved the accuracy of sonar image recognition to varying degrees. At the same time, the proposed algorithm is lightweight and can be deploy on embedded devices. Full article

Background/Objectives: Individuals with chronic stroke often experience various impairments, including poor balance, reduced mobility, limited physical activity, and difficulty performing daily tasks. In the context of the COVID-19 pandemic, telerehabilitation (TR) can overcome the barriers of geographical and physical distancing, time, costs, and travel, as well as the anxiety about contracting COVID-19. In this retrospective case-control study, we aim to evaluate the motor and cognitive effects of balance TR training carried out with a sensor-based non-immersive virtual reality system compared to conventional rehabilitation in chronic stroke patients. Methods: Twenty chronic post-stroke patients underwent evaluation for inclusion in the analysis through an electronic recovery data system. The patients included in the study were divided into two groups with similar medical characteristics and duration of rehabilitation training. However, the groups differed in the type of rehabilitation approach used. The experimental group (EG) received TR with a sensor-based VR device, called VRRS—HomeKit (n. 10). In contrast, the control group (CG) underwent conventional home-based rehabilitation (n. 10). Results: At the end of the training, we observed significant improvements in the EG in the 10-m walking test (10MWT) (p = 0.01), Timed-Up-Go Left (TUG L) (p = 0.01), and Montreal Cognitive Assessment (MoCA) (p = 0.005). Conclusions: In our study, we highlighted the potential role of sensor-based virtual reality TR in chronic stroke patients for improving lower limb function, suggesting that this approach is feasible and not inferior to conventional home-based rehabilitation. Full article

In this work, the transport properties of charge carriers in $\beta$-Ga${}_2$O${}_3$ were investigated, along with intrinsic physical mechanisms such as lattice vibrations, impurity scattering, and interfacial effects. The high-field behavior of carrier mobility was characterized using vacuum deposition techniques for the fabrication of electrodes with ohmic contacts, and the Hall effect measurement system was employed to test the temperature-dependent mobility of Sn-doped n-type (100) and (001) $\beta$-Ga${}_2$O${}_3$ samples at a cryogenic temperature. A predictive model for $\beta$-Ga${}_2$O${}_3$ mobility was developed by examining the effects of the temperature on the scattering mechanisms based on a theoretical transport model. The experimental results for $\beta$-Ga${}_2$O${}_3$ mobility, which varied with the temperature and doping concentration, showed good agreement with the theoretical model within the temperature range of 15–300 K. The maximum discrepancy between the predictive model and the experimental data was less than 5%. This study provides valuable theoretical insights for the design and simulation of $\beta$-Ga${}_2$O${}_3$ devices. Full article

The electrical conductivity of nanocrystalline CuMnO₂ samples, obtained by microwave-assisted hydrothermal synthesis (MWH), is studied by impedance spectroscopy over a frequency range of 30 Hz to 2 MHz and a temperature range from 30 to 120 °C. Three samples are prepared to start from a mixture of sulphate reactants, at two synthesis temperatures and different reaction times (of applying microwaves): sample S1 at 80 °C for 5 min; sample S2 at 120 °C for 5 min and sample S3 at 120 °C for one hour. The static conductivity values, σ_DC of samples S2 and S3, are approximately equal but larger than those of sample S1. This result suggests that using MWH synthesis at 120 °C, with different reaction times (samples S2 and S3), is sufficient for microwaves to be applied for at least 5 min to obtain samples with similar electrical properties. The experimental data were analysed based on three theoretical models, demonstrating that the most appropriate theoretical model to explain the electrical conduction mechanism in the samples is Mott’s variable range hopping (VRH) model. Using this model, the activation energy of conduction, (E_A,cond), the density of localized states near the Fermi level, N(E_F), the hopping distance, R_h(T), the hopping energy, W_h(T) and the charge carrier mobility (μ) were determined for the first time, for microwave-assisted hydrothermally synthesized crednerite. Additionally, the band gap energy (W_m) and hopping frequency (ω_h) were evaluated at various temperatures T. Understanding the electrical conduction mechanism in the polycrystalline CuMnO₂ materials is important for their use in photo-electrochemical and photocatalytic applications, photovoltaic devices, and, more recently, in environmental protection. Full article