Search Results (1,552)

As the core device for protecting the safety of the pressure-bearing system, the spring full-open safety valve is prone to various forms of valve seat sealing surface damage after long-term opening and closing impact, corrosion, and medium erosion, which may lead to internal leakage. In view of the problems that the high-frequency acoustic emission signal of the internal leakage of the safety valve has, namely, a large number of energy-overlapping areas in the frequency domain, the overall signal presents broadband characteristics, large noise content, and no obvious time–frequency characteristics. A composite denoising method, IWTD, improved wavelet threshold function with dual adjustable factors, and the improved VMD algorithm is proposed. In view of the problem that the optimal values of the dual adjustment factors a and b of the function are difficult to determine manually, an improved dung beetle optimization algorithm is proposed, with the maximum Pearson coefficient as the optimization target; the optimization is performed within the value range of the dual adjustable factors a and b, so as to obtain the optimal value. In view of the problem that the key parameters K and α in VMD decomposition are difficult to determine manually, the maximum Pearson coefficient is taken as the optimization target, and the improved dung beetle algorithm is used to optimize within the value range of K and α, so as to obtain the IVMD algorithm. Based on the IVMD algorithm, the characteristic decomposition of the internal leakage acoustic emission signal occurs after the denoising of the IWTD function is performed to further improve the denoising effect. The results show that the Pearson coefficients of all types of internal leakage acoustic emission signals after IWTD-IVMD composite noise reduction are greater than 0.9, which is much higher than traditional noise reduction methods such as soft and hard threshold functions. Therefore, the IWTD-IVMD composite noise reduction method can extract more main features out of the measured spring full-open safety valve internal leakage acoustic emission signals, and has a good noise reduction effect. Feature recognition after noise reduction can provide a good evaluation for the safe operation of the safety valve. Full article

A particularly important activity carried out by railway infrastructure managers to maintain railway devices in full working order is the diagnostic process. It increases the level of railway safety. The diagnostic process involves collecting information about the equipment through inspections, tests, functional trials, parameter measurements, and analysis of the working environment, followed by comparing the obtained information with the required parameters or permissible conditions. This activity also enables the formulation of a technical diagnosis regarding the current ability of the devices to perform its intended functions, taking into account the impact of its technical condition on railway traffic safety. This is especially important in the case of railway traffic control devices, as these devices are largely responsible for ensuring railway traffic safety. The collection of data on the condition of railway traffic control devices in the form of Big Data sets and diagnostic inference is an effective factor in making operational decisions for such devices. It enables the acquisition of complete information about the actual course of the exploitation process and allows for obtaining reliable information necessary to manage this process, particularly in the areas of diagnostics forecasting of devices conditions, renewal, and organization of maintenance and repair facilities. To support this, a service data acquisition and analysis system for railway traffic control devices (SADEK) was developed. This system can serve as a software platform for maintenance needs in the railway sector. Full article

Ion beam figuring (IBF) is an ultra-high-precision surface finishing technology characterized by a distinct trade-off between the spot size of the removal function and its corresponding figuring capabilities. A larger spot size for the removal function leads to higher processing efficiency but lower figuring ability. Conversely, a smaller spot size results in higher figuring ability but lower efficiency. Adjusting the spot size of the removal function using tools with an aperture is a possible approach. However, existing variable-aperture tools have certain limitations in IBF processing. To leverage the advantages of both large and small spot sizes for the removal function during IBF processing, an in situ dynamic beam variable-aperture device has been designed. This device optimizes the parameters of diaphragm sheets and employs FOC for dynamic aperture adjustment. Simulations show that 12 numbers of 0.1 mm-thick sheets minimize removal function distortion, with the thermal strain-induced area variation being <5%. FOC enables rapid (≤0.45 s full range) and precise aperture control. Experiments confirm adjustable spot sizes (FWHM 0.7–17.2 mm) with Gaussian distribution (correlation >96.7%), operational parameter stability (relative change rate ≤5%), and high repeatable positioning precision (relative change rate ≤3.2% in repeated adjustments). The design enhances IBF efficiency, flexibility, and accuracy by enabling in situ spot size optimization, overcoming conventional limitations. Full article

Background/Objectives: To review the dimensions of the round window region (round window niche, bony structures surrounding the niche, and the membrane itself). Methods: Medline, EMBASE, Cochrane Library, and Google Scholar databases were searched by two independent reviewers. Anatomical and radiological studies on the round window region were screened. Studies reporting at least one dimension for the round window (RW) niche and/or the RW membrane were included. Results: Sixteen studies met the inclusion criteria (13 anatomical and 3 radiological studies) for a total number of 808 temporal bones with at least one dimension reported. The structures measured varied across the different studies with 12 reporting RW membrane dimensions (area and/or at least one distance), 8 detailing RW niche dimensions (height, width or depth) and 6 which measured at least one element of the RW bony overhangs (posterior or anterior pillar, RW tegmen). Surface area of the RW membrane varied between 0.32 mm² and 2.89 mm², with a minimum dimension (minimum diameter or height or width) comprising between 0.51 mm and 2.1 mm. When the bony overhangs surrounding the membrane were not considered, the minimum diameter was between 1.65 mm and 1.97 mm. Conclusions: The dimensions of the RW region are intrinsically variable, but the heterogeneity of the measurements reported also contributes to these variations. Posterior pillar, RW tegmen, anterior pillar, and their relative development probably account for a large part of this variability. The future RW membrane devices should be ≤1 mm in their maximum dimension, whether or not individually tailored, to fit most of the RW membranes. Full article

Distributed photovoltaic storage charging piles in remote rural areas can solve the problem of charging difficulties for new energy vehicles in the countryside, but these storage charging piles contain a large number of power electronic devices, and there is a risk of resonance in the system under weak grid conditions. Firstly, the topology of a photovoltaic storage charging pile is introduced, including a bidirectional DC/DC converter, unidirectional DC/DC converter, and single-phase grid-connected inverter. Then, the maximum power tracking control strategy based on improved conductance micro-increment is derived for a photovoltaic power generation system, and a constant voltage and constant current charge–discharge control strategy is derived for energy storage equipment. Additionally, a segmented reflective charging control strategy is introduced for charging piles, and the quasi-PR controller is introduced for single-phase grid-connected inverters. In addition, an improved second-order general integrator phase-locked loop (SOGI-PLL) based on feed-forward of the grid current is derived. Finally, a simulation model is built to verify the performance of the solar–storage charging pile and lay the technical groundwork for future integrated control strategies. Full article

Background and Objectives: Three-dimensional (3D) scanning is increasingly utilized in medical practice, from orthotics to surgical planning. However, traditional hand measurement techniques remain inconsistent and prone to human error and are often time-consuming. This research evaluates the practicality of a commercial 3D scanning method by comparing the accuracy of scans conducted by two user groups. Materials and Methods: This study evaluated the following two groups: an experimental group (n = 45) and a control group (n = 42). A total of 261 hand scans were captured using the Structure Sensor Pro 3D scanner for iPad (Structure, Boulder, CO, USA). The scans were then evaluated using Meshmixer software (version 3.5.474), analyzing key parameters, such as surface area, volume, number of vertices, and triangles, etc. Furthermore, a digital literacy test and a user experience survey were conducted to support a more comprehensive evaluation of participant performance within the study. Results: The experimental group outperformed the control group on all measured parameters, including surface area, volume, vertices, triangle, and gap count, with large effect sizes observed. User experience data revealed that participants in the experimental group rated the 3D scanner significantly higher across all dimensions, particularly in ease of use, excitement, supportiveness, and practicality. Conclusions: A short 15 min training session can promote scan reliability, demonstrating that even minimal instruction improves users’ proficiency in 3D scanning, fundamental for supporting clinical accuracy in diagnosis, surgical planning, and personalized device manufacturing Full article

Air quality monitoring IoT is one of the approaches to achieving a sustainable future. However, the large area of IoT and the high number of monitoring microsites pose challenges for device maintenance to guarantee quality of service (QoS) in monitoring. This paper proposes a novel maintenance programming model for a large-area IoT containing 1500 monitoring microsites. In contrast to classic device maintenance, the addressed programming scenario considers the division of appropriate microsites into batches, the determination of the batch maintenance date, vehicle routing for the delivery of maintenance services, and a set of hard constraints such as QoS in air quality monitoring, the maximum number of labor working hours, and an upper limit on the total CO₂ emissions. Heuristics are proposed to generate the batches of microsites and the scheduled maintenance date for the batches. A genetic algorithm is designed to find the shortest routes by which to visit the batch microsites by a fleet of vehicles. Simulations are conducted based on government open data. The experimental results show that the maintenance and transportation costs yielded by the proposed model grow linearly with the number of microsites if the fleet size is also linearly related to the microsite number. The mean time between two consecutive cycles is around 17 days, which is generally sufficient for the preparation of the required maintenance materials and personnel. With the proposed method, the decision-maker can circumvent the difficulties in handling the hard constraints, and the allocation of maintenance resources, including budget, materials, and engineering personnel, is easier to manage. Full article

This paper presents a novel framework for optimizing multimodal large language model (MLLM) inference through task offloading and resource allocation in UAV-assisted satellite edge computing (SEC) networks. MLLMs leverage transformer architectures to integrate heterogeneous data modalities for IoT applications, particularly real-time monitoring in remote areas. However, cloud computing dependency introduces latency, bandwidth, and privacy challenges, while IoT device limitations require efficient distributed computing solutions. SEC, utilizing low-earth orbit (LEO) satellites and unmanned aerial vehicles (UAVs), extends mobile edge computing to provide ubiquitous computational resources for remote IoTDs. We formulate the joint optimization of MLLM task offloading and resource allocation as a mixed-integer nonlinear programming (MINLP) problem, minimizing latency and energy consumption while optimizing offloading decisions, power allocation, and UAV trajectories. To address the dynamic SEC environment characterized by satellite mobility, we propose an action-decoupled soft actor–critic (AD-SAC) algorithm with discrete–continuous hybrid action spaces. The simulation results demonstrate that our approach significantly outperforms conventional deep reinforcement learning methods in convergence and system cost reduction compared to baseline algorithms. Full article

Polymer-based photonic sensors are emerging as cost-effective, scalable alternatives to conventional silicon and glass photonic platforms, offering unique advantages in flexibility, functionality, and manufacturability. This review provides a comprehensive assessment of recent advances in polymer photonic sensing technologies, focusing on material systems, fabrication techniques, device architectures, and application domains. Key polymer materials, including PMMA, SU-8, polyimides, COC, and PDMS, are evaluated for their optical properties, processability, and suitability for integration into sensing platforms. High-throughput fabrication methods such as nanoimprint lithography, soft lithography, roll-to-roll processing, and additive manufacturing are examined for their role in enabling large-area, low-cost device production. Various photonic structures, including planar waveguides, Bragg gratings, photonic crystal slabs, microresonators, and interferometric configurations, are discussed concerning their sensing mechanisms and performance metrics. Practical applications are highlighted in environmental monitoring, biomedical diagnostics, and structural health monitoring. Challenges such as environmental stability, integration with electronic systems, and reproducibility in mass production are critically analyzed. This review also explores future opportunities in hybrid material systems, printable photonics, and wearable sensor arrays. Collectively, these developments position polymer photonic sensors as promising platforms for widespread deployment in smart, connected sensing environments. Full article

One of the key challenges in commercializing proton exchange membrane (PEM) electrolyzer technology is reducing the production costs while maintaining high efficiency and operational stability. Significant contributors to the overall cost of the device are the electrode catalysts with IrO₂ and Pt/C. Due to the high cost and limited availability of noble metals, there is growing interest in developing alternative, low-cost catalytic materials. In recent years, two-dimensional transition metal dichalcogenides (2D TMDCs), such as molybdenum disulfide (MoS₂) and rhenium disulfide (ReS₂), have attracted considerable attention due to their promising electrochemical properties for hydrogen evolution reactions (HERs). These materials exhibit unique properties, such as a high surface area or catalytic activity localized at the edges of the layered structure, which can be further enhanced through defect engineering or phase modulation. To increase the catalytically active surface area, the investigated materials were deposited on a carbon-based support—Vulcan XC-72R—selected for its high electrical conductivity and large specific surface area. This study investigated the physicochemical and electrochemical properties of six catalyst samples with varying MoS₂ and ReS₂ to carbon support ratios. Among the composites analyzed, the best sample on MoS₂ (containing the most carbon soot) and the best sample on ReS₂ (containing the least carbon soot) were selected. These were then used as cathode catalysts in an experimental PEM electrolyzer setup. The results confirmed satisfactory catalytic activity of the tested materials, indicating their potential as alternatives to conventional noble metal-based catalysts and providing a foundation for further research in this area. Full article

Over the past two decades, titanium dioxide nanotubes (TiO₂ NTs) have gained considerable attention as multifunctional materials in sensing technologies. Their large surface area, adjustable morphology, chemical stability, and photoactivity have positioned them as promising candidates for diverse sensor applications. This review presents a broad overview of the development of TiO₂ NTs in sensing technologies for medical diagnostics over the last two decades. It further explores strategies for enhancing their sensing capabilities through structural modifications and hybridization with nanomaterials. Despite notable advancements, challenges such as device scalability, long-term operational stability, and fabrication reproducibility remain. This review outlines the evolution of TiO₂ NT-based sensors for medical diagnostics, highlighting both foundational progress and emerging trends, while providing insights into future directions for their practical implementation across scientific and industrial domains. Full article

Traditional PMUT ultrasonic ranging systems usually possess a large measurement blind area under the integrated transmit–receive mode, dramatically limiting its distance measurement in confined spaces, such as when determining the clearance of large bearing components. Here, a broadband PMUT rangefinder was designed by integrating six types of different cells with adjacent resonant frequencies into an array. Through overlapping and coupling of the bandwidths from the different cells, the proposed PMUTs showed a wide –6 dB fractional bandwidth of 108% in silicon oil. Due to the broadening of bandwidth, the device could obtain the maximum steady state with less excitation (5 cycles versus 14 cycles) and reduce its residual ring-down (ca. 6 μs versus 15 μs) compared with the traditional PMUT array with the same cells, resulting in a small blind area. The pulse–echo ranging experiments demonstrated that the blind area was effectively reduced to 4.4 mm in air or 12.8 mm in silicon oil, and the error was controlled within ±0.3 mm for distance measurements up to 250 mm. In addition, a specific ultrasound signal processing circuit with functions of transmitting, receiving, and processing ultrasonic waves was developed. Combining the processing circuit and PMUT device, the system was applied to determine the axial clearance of the main bearing in a tunneling machine. This work develops broadband PMUTs with a small blind area and high resolution for distance measurement in narrow and confined spaces, opening up a new path for ultrasonic ranging technology. Full article

Microfluidic devices are used in numerous scientific fields and research areas, but device fabrication is still a time- and resource-intensive process largely confined to the cleanroom or a similarly well-equipped laboratory. This paper presents a method to create microfluidic devices in under three hours using the silicone polymer polydimethylsiloxane (PDMS) and a laser cut positive master using PDMS double casting without a cleanroom or other large capital equipment. This method can be utilized by an undergraduate student with minimal training in a laboratory with a modest budget. This paper presents “Same Day Microfluidics” as a fabrication method accessible to research groups not currently fabricating their own microfluidic devices and as an option for established research groups to more quickly create prototype devices. The method is described in detail with timing, materials, and technical considerations for each step and demonstrated in the context of a Y-channel coflow device. Full article

Heterojunctions are commonly used in optoelectronic devices to improve device performance. However, interface defects and lattice mismatch often hinder carrier transport and reduce efficiency, emphasizing the need for further exploration of diverse heterojunction structures. In this study, a heterojunction device constructed from Bi₂O₃ and Ga₂O₃ is demonstrated. The microstructures and photoelectrical properties of Bi₂O₃ and Ga₂O₃ thin films were investigated. Bi₂O₃ and Ga₂O₃ thin films show a bandgap of 3.19 and 5.10 eV. The Bi₂O₃/Ga₂O₃ heterojunction-based device demonstrates rectification characteristics, with a rectification ratio of 2.72 × 10³ at ±4.5 V and an ON/OFF ratio of 1.07 × 10⁵ (4.5/−3.9 V). Additionally, we fabricated a sandwich-structured photodetector based on the Bi₂O₃/Ga₂O₃ heterojunction and investigated its ultraviolet photoresponse performance. The photodetector exhibits low dark current (0.34 pA @ −3.9 V) and fast response rise/fall time (<40/920 ms). This work offers important perspectives on the advancement of large-area, low-cost, and high-speed Bi₂O₃ film-based heterojunction photodetectors. Full article

In this study, zinc–tin oxide (ZTO) thin films were prepared via radio-frequency magnetron sputtering to examine the influence of annealing temperature on the performance of thin-film transistors (TFTs) and their resistive-load inverters. The findings reveal that annealing modulates the concentration and spatial distribution of oxygen vacancies (V_O), which directly affect carrier density and interface trap density, ultimately determining the electrical behavior of inverters. At the optimal annealing temperature of 600 °C, the V_O concentration was effectively moderated, resulting in a TFT with a mobility of 12.39 cm² V⁻¹ s⁻¹, a threshold voltage of 6.13 V, an on/off current ratio of 1.09 × 10⁸, and a voltage gain of 11.77 in the corresponding inverter. However, when the V_O concentration deviated from this optimal range, whether in excess or deficiency, the gain was reduced and power consumption increased. This V_O engineering strategy enables the simultaneous optimization of both TFT and inverter performance without relying on rare elements, offering a promising pathway toward the development of low-cost, large-area, flexible, and transparent electronic devices. Full article