Search Results (661)

This paper presents an experimental evaluation of the connectivity reliability of a LoRaWAN (Long Range Wide Area Network), deployed in a rural area of Mozambique, focusing on the influence of distance and relative altitude between end nodes and the gateway. The absence of telecommunications and power infrastructure in the study region provided a realistic and challenging scenario to assess LoRaWAN’s feasibility as a low-cost, low-power solution for remote sensing in disconnected environments. Field trials were conducted using an Arduino-based node (with 2 dBi antenna) powered by a 2200 mAh power bank, with no GPS or cellular support. Data were collected at four georeferenced points along a 1 km path, capturing Received Signal Strength Indicator (RSSI), Signal-to-Noise Ratio (SNR), and Packet Delivery Rate (PDR). Results confirmed that both distance and terrain elevation strongly affect performance, with significantly degraded metrics when the end nodes were located at lower altitudes relative to the gateway. Despite operational constraints, such as the need for manual firmware resets and lack of real-time monitoring, the network consistently achieved PDR above 89% and remained operational autonomously for over 24 h. The study highlights the effectiveness of installing gateways on natural elevations to improve coverage and demonstrates that even with basic hardware, LoRaWAN (Low Power Wide Area Network), is a viable and scalable option for rural connectivity. These findings offer valuable empirical evidence to promote national digital inclusion policies and future LPWAN deployments. Full article

Future wireless networks are expected to deliver enhanced spectral efficiency while being energy efficient. MIMO and other non-orthogonal transmission schemes, such as non-orthogonal multiple access (NOMA), offer substantial theoretical spectral efficiency gains. However, these gains have yet to translate into practical deployments, largely due to limitations in current signal processing methods. Linear transceiver processing, though widely adopted, fails to fully exploit non-orthogonal transmissions, forcing massive MIMO systems to use a disproportionately large number of RF chains for relatively few streams, increasing power consumption. Non-linear processing can unlock the full potential of non-orthogonal schemes but is hindered by high computational complexity and integration challenges. Moreover, existing message-passing receivers for NOMA depend on specially designed sparse signals, limiting resource allocation flexibility and efficiency. This work presents NL-COMM, an efficient non-linear processing framework that translates the theoretical gains of non-orthogonal transmissions into practical benefits for both the uplink and downlink. NL-COMM delivers over 200% spectral efficiency gains, enables 50% reductions in antennas and RF chains (and thus base station power consumption), and increases concurrently supported users by 450%. In distributed MIMO deployments, the antenna reduction halves fronthaul bandwidth requirements, mitigating a key system bottleneck. Furthermore, NL-COMM offers the flexibility to unlock new NOMA schemes. Finally, we present both hardware and software architectures for NL-COMM that support massively parallel execution, demonstrating how advanced non-linear processing can be realized in practice to meet the demands of next-generation networks. Full article

Deep-well radar telemetry over ultra-long cables suffers from strong frequency-selective attenuation and impedance drift under high temperature and pressure. We have proposed a channel-adaptive “communication + acquisition” architecture for a 7500 m borehole radar system. The scheme integrates spread-spectrum time domain reflectometry (SSTDR; m-sequence with BPSK) to monitor the cable in situ, identify termination/cable impedance, and adaptively match the load, thereby reducing reflection-induced loss. On the receiving side, we combine time domain adaptive equalization—implemented as an LMS-driven FIR filter—with frequency domain OFDM equalization based on least-squares (LS) channel estimation, enabling constellation recovery and robust demodulation over the distorted channel. The full processing chain is realized in real time on a Xilinx Artix-7 (XC7A100T) FPGA with module-level reuse and pre-stored training sequences for efficient hardware scheduling. In a field deployment in the Shunbei area at 7500 m depth, radar results show high agreement with third-party geological logs: the GR-curve correlation reaches 0.92, the casing reflector at ~7250 m is clearly reproduced, and the key bottom depth error is 0.013%. These results verify that the proposed system maintains stable communication and accurate imaging in harsh deep-well environments while remaining compact and implementable on cost-effective hardware. Full article

Background: Sepsis is a leading cause of morbidity and mortality among patients receiving maintenance hemodialysis (HD), reflecting a unique combination of immunologic dysfunction, comorbidities, and healthcare-related exposures. Despite advances in dialysis technology and infection control, outcomes for septic HD patients remain disproportionately poor. Objective: This review aims to synthesize current evidence on the epidemiology, risk factors, diagnostic challenges, and treatment considerations of sepsis in HD patients, highlighting persistent vulnerabilities and areas for clinical improvement. Methods: A structured narrative review was conducted, focusing on high-quality cohort studies, surveillance data, and pharmacologic analyses published over the past two decades. The literature search was performed using PubMed, Web of Science, and Google Scholar. A total of 37 studies were included in the final synthesis. Key themes were organized around epidemiologic trends, infection sources, risk modifiers, treatment outcomes, and antimicrobial considerations in the dialysis population. Results: The review found that sepsis in HD patients is multifactorial and systemic. Diabetes, advanced age, and central venous catheters remain strong risk factors, while a substantial proportion of infections arise from non-access-related sources. Mortality rates remain high, often due to delays in recognition, inappropriate empiric therapy, and challenges in antimicrobial dosing. Pharmacokinetic alterations in renal replacement therapy complicate treatment, requiring individualized approaches. Despite variations in infection rates across centers, systemic vulnerabilities—rather than dialysis modality alone—drive outcomes. Conclusions: Sepsis in hemodialysis patients is not solely a hardware-related complication but reflects deeper systemic and immunologic challenges. Improving outcomes will require earlier recognition, tailored antimicrobial strategies, standardized infection control protocols, and broader attention to patient-specific risk factors. Future research should focus on ESRD-adapted sepsis diagnostics and interventional models to reduce infection-related mortality in this high-risk group. Full article

We propose a speed-adapted treadmill that can be incorporated into a rehabilitation trainer that applies neurodevelopmental treatment (NDT) for patients with stroke. NDT practice is effective for post-stroke patients, but its requirement for therapists’ participation can limit the patients’ rehabilitation during the golden period of recovery. Previous studies have proposed a trainer that can automatically reiterate therapists’ interventions. However, that trainer employed a constant-speed treadmill, which required the users to frequently adjust their walking speeds during rehabilitation. This paper develops a speed-adapted treadmill that can regulate the treadmill motor to maintain the subject’s position during the training process. First, we derive models of the treadmill and cable motors through experiments. Then, we design robust controls for the two systems and simplify them as proportional-integral-derivative controllers for hardware implementation. Finally, we integrate the system and invite healthy and stroke subjects to participate in clinical experiments. Among ten stroke subjects, all subjects’ walking speeds and nine subjects’ stride lengths were improved, while eight subjects showed improvement in the swing-phase asymmetry and pelvic rotation after receiving the NDT rehabilitation employing the speed-adapted treadmill. Our findings indicate that the NDT trainer effectively enhances users’ gait characteristics, including swing-phase symmetry, pelvic rotation, walking speed, and stride length. Full article

Wideband oscillation events, with frequencies ranging from several hertz to several kilohertz, have been frequently reported in modern power systems, posing significant challenges to grid stability and sustainability. In response, technologies for oscillation monitoring and analysis have received increasing attention. However, most existing technologies still rely primarily on traditional wide-area measurement systems, which struggle to meet the requirements for wideband oscillation monitoring. This paper first presents a comprehensive review of recent wideband oscillation events reported worldwide, highlighting their causes and adverse impacts on equipment security and system stability. Subsequently, a novel framework for a wideband dynamic monitoring and control system (WDMCS) is proposed, along with detailed descriptions of its principal components and key functions related to wideband oscillations. Finally, a demonstration of WDMCS has been developed, and its effectiveness has been validated through tests conducted on a hardware-in-the-loop platform. The potential and challenges of the proposed system in various domains of power system stability assessment and control are also discussed. Full article

Effective means are urgently needed to identify non-cooperative targets intruding on airport clearance zones for the safety of low-altitude flights. Passive radars are an ideal means of low-altitude airspace surveillance for their low costs in terms of hardware and operation. However, non-ideal signals transmitted by third-party illuminators challenge feature extraction and target recognition in such radars. To tackle this problem, we propose a light-weight recognition-before-tracking method based on a beam constraint for passive radars. Under the background of sparse targets, the proposed method utilizes the continuity of target motion to identify the same target from the same array beam. Then, with its peaks detected in range-Doppler maps, a feature vector based on the biased radar cross-section is constructed for recognition. Meanwhile, to use the local scattering characteristics of targets for dynamic recognition, we introduce a parameter named normalized bistatic velocity to characterize the attitude of the target relative to the receiving station. With the proposed light-weight metric, the similarity of feature vectors between the unknown target and standard targets is measured to determine the target type. The feasibility and effectiveness of the proposed method are validated by the simulated and measured data. Full article

Objectives: Operative fixation of displaced midshaft clavicle fractures has become increasingly the more acceptable choice of care in recent years, based on evidence supporting its effectiveness. However, this practice presents challenges due to the complex S-shaped morphology of the clavicle and its subcutaneous location. Despite the introduction of anatomically pre-contoured plates, achieving optimal implant-to-bone fit remains difficult, prompting the development of newer plate generations. The aim of this study was to compare the hardware removal rates of second-generation 2.7 mm thinner plates (SGPs) with those of first-generation 3.5 mm plates (FGPs). Methods: A retrospective comparative cohort study was conducted at a level one trauma center. A total of 187 patients received FGPs, and 67 received SGPs, both positioned on the superior bone surface. All surgeries were performed by fellowship-trained surgeons, and patients were followed for at least one year. Data were extracted from medical records and the PACS system. Results: The patients’ demographics (age: 32.86 vs. 33.14 years; gender: 16.85% vs. 14.92% female) and fracture type (AO/OTA) were similar between the two groups. The rate of implant removal (20.1% vs. 20.9%) did not differ significantly between groups. Complications included nonunion (1.6% vs. 1.7%, statistically not significant) and infection (three cases in the FGP group, none in the SGP group). Conclusions: Despite the high success rate of clavicle fixation procedures, the superior clavicular plate removal rate remains significant, regardless of the implant design. Full article

In the era of artificial intelligence, neuromorphic devices that simulate brain functions have received increasingly widespread attention. In this paper, an artificial neural synapse device based on ZnAlSnO thin-film transistors was fabricated, and its electrical properties were tested: the current-switching ratio was 1.18 × 10⁷, the subthreshold oscillation was 1.48 V/decade, the mobility was 2.51 cm²V⁻¹s⁻¹, and the threshold voltage was −9.40 V. Stimulating artificial synaptic devices with optical signals has the advantages of fast response speed and good anti-interference ability. The basic biological synaptic characteristics of the devices were tested under 365 nm light stimulation, including excitatory postsynaptic current (EPSC), paired-pulse facilitation (PPF), short-term plasticity (STP), and long-term plasticity (LTP). This device shows good synaptic plasticity. In addition, by changing the gate voltage, the excitatory postsynaptic current of the device at different gate voltages was tested, two different logical operations of “AND” and “OR” were achieved, and the influence of different synaptic states on memory was simulated. This work verifies the application potential of the device in the integrated memory and computing architecture, which is of great significance for promoting the high-quality development of neuromorphic computing hardware. Full article

In space applications, the required levels of performance and reliability drive up hardware costs. Reducing the efforts related to device development and validation may help balance the budget. A versatile transmitter for space telemetry is implemented here that may help in this respect. Such a device can switch across different linear and continuous phase modulation schemes just by modifying its parameters, while maintaining the same hardware structure. Results from an extensive campaign of experimental test measurements of the device are reported. A GNURadio-implemented receiver is developed to test performance of the actual transmitter by considering all the main blocks of the receiver chain and computing the bit error rate (BER) at the receiver. After testing different configurations, results confirm that the BER of the improved one-filter modulated signal is lower than the BER obtained using only the first Laurent decomposition component. Full article

The rapid growth of Internet-connected devices integrating into our everyday lives has no end in sight. As more devices and sensor networks are manufactured, security tends to be a low priority. However, the security of these devices is critical, and many current research topics are looking at the composition of simpler techniques to increase overall security in these low-power commercial devices. Transmission security (TRANSEC) methods are one option for physical-layer security and are a critical area of research with the increasing reliance on the Internet of Things (IoT); most such devices use standard low-power Time-division multiple access (TDMA) or frequency-division multiple access (FDMA) protocols susceptible to reverse engineering. This paper provides a hardware validation of previously proposed techniques for the intentional injection of noise into the phase mapping process of a spread spectrum signal used within a receiver-assigned code division multiple access (RA-CDMA) framework, which decreases an eavesdropper’s ability to directly observe the true phase and reverse engineer the associated PRNG output or key and thus the spreading sequence, even at high SNRs. This technique trades a conscious reduction in signal correlation processing for enhanced obfuscation, with a slight hardware resource utilization increase of less than 2% of Adaptive Logic Modules (ALMs), solidifying this work as a low-power technique. This paper presents the candidate method, quantifies the expected performance impact, and incorporates a hardware-based validation on field-programmable gate array (FPGA) platforms using arbitrary-phase phase-shift keying (PSK)-based spread spectrum signals. Full article

The growing number of connected devices has strained traditional radio frequency wireless networks, driving interest in alternative technologies such as optical wireless communications (OWC). Among OWC solutions, optical camera communication (OCC) stands out as a cost-effective option because it leverages existing devices equipped with cameras, such as smartphones and security systems, without requiring specialized hardware. This paper proposes a novel deep learning-based detection and classification model designed to optimize the receiver’s performance in an OCC system utilizing color-shift keying (CSK) modulation. The receiver was experimentally validated using an $8\times 8$ LED matrix transmitter and a CMOS camera receiver, achieving reliable communication over distances ranging from 30 cm to 3 m under varying ambient conditions. The system employed CSK modulation to encode data into eight distinct color-based symbols transmitted at fixed frequencies. Captured image sequences of these transmissions were processed through a YOLOv8-based detection and classification framework, which achieved $98.4$% accuracy in symbol recognition. This high precision minimizes transmission errors, validating the robustness of the approach in real-world environments. The results highlight OCC’s potential for low-cost applications, where high-speed data transfer and long-range are unnecessary, such as Internet of Things connectivity and vehicle-to-vehicle communication. Future work will explore adaptive modulation and coding schemes as well as the integration of more advanced deep learning architectures to improve data rates and system scalability. Full article

To support NASA’s mission to use nuclear thermal rockets for future Mars missions, an instrumentation and control test bed has been built at Oak Ridge National Laboratory. The system is designed as a hardware-in-the-loop test bed for testing control elements and autonomous control algorithms for nuclear thermal propulsion rockets. The mock reactor system consists of a modular and scalable framework, using inexpensive components and open-source software. The hardware system consists of a two-phase flow loop and a mock reactor with six control drums. A single-board computer (NVIDIA Jetson) handles reactor core emulation and hosts a message queuing telemetry transport broker that allows user-deployed control algorithms to interact with the system hardware. The reactor emulator receives sensor data from the hardware and provides the simulated performance of the reactor under steady-state, transient, and fault conditions. The emulator uses a reactivity lookup table and the point kinetics equations to solve for the reactor dynamics in real time. Emulated reactor dynamics and sensor input inform the autonomous control algorithm’s decision-making in a closed-loop manner. The current system is capable of operating at 10 Hz, but faster cycle rates are an area of ongoing research. This test bed will enable NASA and other space vendors to rigorously test their autonomous control systems for NTP rockets under transient (reactor startup and shutdown), steady-state, and fault conditions to reduce development time and risk for autonomous control systems in future missions. Full article

Background and Objectives: Reconstructive outcomes following head and neck (H&N) cancer resection in pediatric patients remain understudied, particularly regarding the comparative efficacy of free versus local tissue transfer. Materials and Methods: A retrospective review was conducted on pediatric patients undergoing malignant H&N tumor resection at a tertiary center from 2007 to 2024. Patients were stratified by reconstruction type (free vs. local flap), and outcomes assessed included flap failure, wound complications, revision rates, operative time, hospital stay, and 30-day readmission. Results: A total of 41 patients (mean age: 10.6 years) met inclusion criteria; 18 underwent free flaps and 23 received local flaps. Common diagnoses included osteosarcoma (21.9%) and rhabdomyosarcoma (12.2%). Anterolateral thigh (44.4%) and fibula (33.3%) were the most common free flaps; temporalis (21.7%) and pectoralis (13.0%) were common local flaps. Flap survival was high in both groups (94.4% vs. 100%). However, local flaps had significantly higher rates of hardware exposure (34.7% vs. 5.5%, p = 0.025) and wound dehiscence (39.1% vs. 5.5%, p = 0.045). Free flaps were associated with longer operative times (10.3 vs. 6.5 h, p = 0.011) and hospital stays (29.1 vs. 13.9 days, p = 0.036). Conclusions: While both approaches achieved high flap survival, free flaps may offer more durable reconstruction and reduce wound-related complications in complex pediatric H&N oncologic cases. Full article

The Internet of Things (IoT) has become an integral part of today’s smart and digitally connected world. IoT devices and technologies now connect almost every aspect of daily life, generating, storing, and analysing vast amounts of data. One important use of IoT is in utility management, where essential services such as water are supplied through IoT-enabled infrastructure to ensure fair, efficient, and sustainable delivery. The large volumes of data produced by water distribution networks must be safeguarded against manipulation, theft, and other malicious activities. Incidents such as the Queensland user data breach (2020–21), the Oldsmar water treatment plant attack (2021), and the Texas water system overflow (2024) show that attacks on water treatment plants, distribution networks, and supply infrastructure are common in Australia and worldwide, often due to inadequate security measures and limited technical resources. Lightweight cryptographic algorithms are particularly valuable in this context, as they are well-suited for resource-constrained hardware commonly used in IoT systems. This study focuses on the in-house developed ChaosFortress lightweight cryptographic algorithm, comparing its performance with other widely used lightweight cryptographic algorithms. The evaluation and comparative testing used an Arduino and a LoRa-based transmitter/receiver pair, along with the NIST Statistical Test Suite (STS). These tests assessed the performance of ChaosFortress against popular lightweight cryptographic algorithms, including ACORN, Ascon, ChaChaPoly, Speck, tinyAES, and tinyECC. ChaosFortress was equal in performance to the other algorithms in overall memory management but outperformed five of the six in execution speed. ChaosFortress achieved the quickest transmission time and topped the NIST STS results, highlighting its strong suitability for IoT applications. Full article