Search Results (2,786)

In modern power systems such as new energy generation and smart grids, inverters serve as core equipment for electrical energy conversion and transmission. Their operational reliability directly impacts system power supply quality and safety stability. Currently, research on inverter fault diagnosis technology primarily focuses on linear load conditions, with diagnostic method design and validation based on linear load characteristics. However, with the rapid advancement of power electronics technology, power electronic loads such as variable frequency drives, charging stations, and distributed power sources are increasingly prevalent in power systems. These loads exhibit nonlinear and time-varying characteristics under complex operating conditions, leading to a growing variety of inverter faults with significantly diversified and complex fault signatures. Traditional diagnostic methods fail to adapt to the unique characteristics of power electronic loads, making it difficult to accurately identify various faults. Consequently, they no longer meet the diagnostic demands of practical engineering scenarios. In addition, current diagnostic methods for open-circuit power transistors, intermittent faults, and sensor faults often employ different approaches, which consume significant controller resources and are prone to mutual interference, leading to false triggers. This paper takes a three-phase four-wire inverter as the research subject. Targeting the challenge of fault diagnosis under power electronic load conditions, it proposes a comprehensive diagnostic method capable of simultaneously diagnosing power switch open circuits, intermittent faults, and current sensor faults. First, the characteristics of various faults are analyzed. Subsequently, fault diagnosis variables are constructed using the actual arm voltage of the inverter and the ideal arm voltage. Logical rules for each type of fault are established, and diagnosis is performed through fuzzy logic inference. Finally, experiments validated the effectiveness of this fault diagnosis scheme, with open-circuit faults detected in less than 2 ms, intermittent faults in less than 0.5 ms, and sensor faults in less than 3 ms. Full article

The intensification and continuous evolution of dairy sheep and goat farming have played an essential role in the development and implementation of milking equipment. The increasing demand for time-efficient milking procedures, reduced labour costs, sustained milk production, and optimal mammary health have driven the widespread adoption and optimisation of machine milking technologies. The objectives of this article are (i) the review of milking systems and relevant technological developments in milking equipment and (ii) the evaluation and description of their impact on udder health, as applied on dairy small ruminant farms. Milking systems used on farms depend on the available space and number of animals on the farms. Appropriate settings in milking systems are important for ensuring good milk quality; among them, vacuum level, pulsation rate and ratio are important characteristics that must be monitored regularly. Further, use of appropriate teatcups specific to the animal species to be milked is significant. An important aspect of proper maintenance of the milking system is the cleaning procedure after completion of milking. Points for consideration are quality and temperature of the water used for cleaning, use of detergents and disinfectants, and maintenance schedule and teatcup replacement. Some technological features that are part of milking systems include automatic vacuum shut off, electronic milk recording, electronic identification of animals, automatic flushing of milking clusters and automatic pre-stimulators. Farms will benefit from applying precision technologies, which will use data from tools related to animal genetic background, animal behavioural indicators, environmental conditions and disease-related functions for more holistic and cost-effective farm management. In this context, integration of sensor-based technologies in milking systems will be able to provide real-time information regarding quality of milk produced at individual and farm levels. Moreover, the introduction of automatic system flushing in-between animals during the milking procedure can contribute to breaking chains of potential bacterial transfer and reducing animal infections during milking. Overall, although machine milking has certainly contributed to improved efficiency, milk quality and labour conditions, flaws in system function may adversely affect mammary health. Full article

Reliable temperature monitoring is essential for the thermal management and safe operation of modern telecommunication equipment. However, conventional temperature sensors are often relatively large and rigid, which limits their applicability for localized temperature measurement on compact electronic components. In this study, a flexible thin-film thermocouple based on NiCr–NiSi thermoelectric materials was developed for temperature monitoring of telecommunication equipment. The sensor adopts a multilayer structure consisting of a polyimide (PI) flexible substrate, an Al₂O₃ insulating layer, NiCr and NiSi thermoelectric films, and a SiO protective layer and was fabricated using magnetron sputtering. Static calibration experiments show that the fabricated sensor exhibits a thermoelectric sensitivity of approximately 40.45 µV/°C, which is close to the reference value of conventional K-type thermocouples, with a relative error of about 1.34%. Repeated heating–cooling cycles demonstrate good repeatability and stable thermoelectric characteristics. Dynamic tests under representative transient thermal conditions showed that the sensor could continuously capture temperature variations without signal interruption or abnormal fluctuations. To further quantify its dynamic behavior, a numerical step-response simulation was performed for the PI/Al₂O₃/NiCr–NiSi/SiO multilayer structure. The simulated thermal time constant and curve-extracted 90% response time were 0.0343 s and 0.0803 s, respectively, under the specified boundary conditions. Owing to its small thickness, low thermal mass, and good mechanical flexibility, the proposed thin-film thermocouple can be conformally attached to compact and curved electronic surfaces, indicating promising potential for real-time localized temperature monitoring of telecommunication equipment and other compact electronic systems. Full article

Large-scale integration of renewable energy sources and power-electronic equipment introduces substantial background harmonics into the grid and, at the same time, gives rise to weak-grid operating conditions with a low short-circuit ratio, thereby degrading the power quality and stability of grid-connected converters. This paper investigates a three-phase LCL-type grid-connected converter and establishes a dq-domain admittance model that incorporates the DC-voltage outer loop, the phase-locked loop (PLL), and grid-voltage feedforward. On the basis of admittance-reshaping theory, a method is proposed to suppress the influence of background harmonics and enhance system stability. First, the frequency coupling caused by the structural asymmetry of the PLL and the voltage outer loop is decoupled to reduce the harmonic components in the grid current. Then, based on the decoupled model, the grid-voltage feedforward path is compensated to eliminate the negative-damping region in the converter output admittance and thus improve system stability under weak-grid conditions. Finally, simulation and experimental results verify the effectiveness of the proposed method. Full article

Objective: The current investigation aims to assess the clinical efficacy of intraoral photographic assessment in detecting dental caries of varying severity and to assess different variables, such as the type of dentition, examiner experience, and the type of imaging equipment, on evaluative clarity. Methods: This meta-analysis of the PRISMA-DTA systematic review and diagnostic test accuracy was conducted. They searched electronic databases such as PubMed, Web of Science, Scopus, Embase, and Cochrane Library from the beginning of time up to January 2025. The studies had to have evaluated intraoral photographic caries because they were required to have compared it with clinical intraoral examination and provide extractable tooth-level 2 × 2 data. Enamel (ICDAS 1 3), dentine (ICDAS 4 6), and any caries (ICDAS 1 6) were analyzed separately in a meta-analysis. A random-effects model was used to compute pooled sensitivity, specificity, diagnostic odds ratio (DOR), and summary receiver operating characteristic (SROC) curves. Subgroup analysis was done on a pre-specified basis according to dentition, type of examiner, and imaging device. This study has been registered in PROSPERO with reference number 2026 CRD420261330820. Results: Twenty-three studies were retrieved through a comprehensive search and were stratified by severity into three categories. In the case of enamel caries, sensitivity was 0.65 (95% CI: 0.62–0.68), specificity was 0.95 (95% CI: 0.94–0.95), DOR was 36.74 (95% CI: 12.44–108.49), and the AUC was 0.87. In the case of dentine caries, the pooled sensitivity and specificity were 0.86 (95% CI: 0.85–0.87) and 0.96 (95% CI: 0.96–0.97), respectively, which produced the DOR of 176 (95% CI: 91.2–339.6) and the AUC of 0.94. Any caries had a pooled sensitivity of 0.81 (95% CI: 0.80–0.83), specificity of 0.97 (95% CI: 0.96–0.97), DOR of 64.04 (95% CI: 11.65–351.94), and AUC of 0.888. Subgroup analyses revealed that diagnostic accuracy was greater when the lesions were severe. Conclusions: Intraoral photographic assessment has a moderate level of accuracy in detecting enamel lesions and has a clinically acceptable level of accuracy in detecting dentine caries. The clinical efficacy increased with the severity of lesions and was consistent with high specificity at all levels of threshold. Imaging on smartphones could be a promising method for caries screening. Full article

Two semiflexible piezoelectric composite plate structures were developed, incorporating 1 × 9 and 2 × 9 arrays of PZT elements mounted on brass discs and mechanically secured by pop rivets within a thin plastic foil spacer positioned between two copper-clad PCB layers. This configuration provides reliable electrical contact, adequate mechanical compliance, and efficient conversion of mechanical vibration energy into electrical energy. In addition, a multifunctional thermoelectric device was realized, consisting of four cubic modules arranged around a rectangular tube and enabling both handheld operation and coupling to hot or cold surfaces. Each cube is equipped with optimized finned heat sinks and integrates four thermoelectric elements on each face. Experimental results show that each cube generates approximately 6 mW, when handheld and with icy water injected into the central tube, demonstrating its suitability as a compact and versatile thermal energy harvester. Under low-light conditions, a solar panel is supplemented by this hybrid piezoelectric–thermoelectric energy harvesting system that combines the output of a piezoelectric composite plate with the dual outputs of a thermoelectric device using an electronically isolated summing block to ensure source decoupling. Energy storage and management are implemented using a capacitor buffer for the piezoelectric device, two voltage boosters for the thermoelectric outputs, and an automatic ultra-low-power pulse width modulation buck regulator for charging supercapacitors at 5 V. Full article

Hepatobiliary surgery is a technically complex subspecialty within general surgery, which requires a comprehensive understanding of complex liver and liver tumour anatomy. The current body of literature highlights the use of three-dimensional-printed liver models (3DPLMs) reconstructed from medical imaging datasets may improve clinician comprehension of patient-specific liver anatomy thus creating a useful tool for hepatobiliary surgical planning and clinician training. The purpose of this systematic review was to examine the clinical utility and feasibility of 3DPLMs in hepatobiliary surgical planning and clinical education and investigate whether these applications influence patient outcomes. Studies were retrieved from three electronic databases (ProQuest, PubMed and Scopus) according to predetermined eligibility criteria. In total, 25 eligible articles were identified, including 18 original research articles and seven case reports. An inductive content analysis approach suitable for heterogeneous bodies of literature was used to synthesise key concepts in this review. There are significant case report and descriptive evidence to support the use of 3DPLMs in clinical education, preoperative planning and intraoperative guidance of patient liver and tumour anatomy to improve hepatobiliary surgical decision making. The studies presented display a large variance in cost and times necessary for the production of 3DPLMs, as studies did not include the software, equipment and full expense of materials used. Additionally, studies concentrated on different aspects of the 3DPLMs production process making them not comparable. This review demonstrates the potential value of 3DPLMs in clinical education, preoperative planning and intraoperative guidance in hepatobiliary anatomy and surgery. Future studies, in particular, randomised controlled trials and experimental research are required to investigate the relationship between 3DPLMs and clinical education and surgical planning outcomes. Full article

In the present study, the development of a high-density polyethylene/polylactic acid/titanium dioxide (HDPE–PLA–TiO₂) composite proposed for pellet-based additive manufacturing and the evaluation of its thermal and mechanical behavior are presented and discussed. The study was designed to address the printability limitations of high-HDPE-content systems, particularly extrusion instability and weak interlayer adhesion. PLA was introduced to improve processing stability, while TiO₂ was incorporated as an inorganic filler. The selected formulation allowed the production of filaments, pellets, and 3D-printed specimens. Thermal analysis indicated the absence of significant mass loss below approximately 300 °C under the applied thermogravimetric/differential thermal analysis (TG/DTA) conditions, suggesting that no major mass-loss degradation occurred within the selected processing window. However, this result should be interpreted as macroscopic thermal stability and does not exclude possible molecular-level changes in PLA during processing. Tensile tests indicated strengths of 20–25 MPa for extruded filaments and 7.86–10.36 MPa for printed specimens, with an elastic modulus of approximately 2 GPa. Scanning Electron microscopy equipped with Energy Dispersive X-Ray Spectroscopy (SEM/EDS) observations revealed a heterogeneous fracture morphology with cavities, microcracks, fibrillar structures, and local Ti-rich regions, supporting the influence of morphology and filler distribution on the mechanical response of the printed specimens. The results indicate improved printability, adequate thermal behavior for the selected processing conditions, and moderate but reproducible tensile performance, highlighting the potential of this formulation for pellet-based additive manufacturing applications where processability and rigidity are more relevant than maximum tensile strength. Full article

Microbially induced corrosion is a common problem in the petroleum industry. In this study, weight loss and surface analysis of grade 20 carbon steel corrosion witness samples were used to evaluate biocorrosion in produced fluids from different wells (Romashkino oilfield, Republic of Tatarstan, Russia). The structure of the resulting microbial communities in the systems with high corrosion indicators was elucidated. The addition of acetate/lactate, yeast extract, and sulfate was found to promote the growth of individual microorganisms in the designed systems and to increase the corrosion rate in several samples (to an average of 0.12 mm year⁻¹). The results of 16S rRNA gene sequence analysis showed that water from different wells from the Romashkino oilfield had distinct microbial compositions. The main genera in the analyzed waters were Oleidesulfovibrio, Halanaerobium, Proteiniphilum, Acetobacterium, Fusibacter, and Methanocrinis, but their relative abundances depended on the water itself and the type of stimulation. Acetogenic bacteria of the genera Fusibacter, Proteiniphilum, Acetobacterium, and acetoclastic methanogenic archaea Methanocrinis became dominant in the microbial community structure in the acetate-enriched systems in water from one of the studied wells. Electron donors, generated by various bacteria and artificially introduced ones, facilitated active dissimilatory sulfate reduction by Oleidesulfovibrio, Desulfotignum, Desulfocurvus, and Pseudodesulfovibrio in water from another production well. The obtained results are important for identifying the causes of premature failures of oilfield equipment, particularly in areas where microbial enhanced oil recovery is used. Full article

To reduce the generation of waste electrical and electronic equipment (WEEE), or electronic waste (hereafter referred to as E-waste), within urban waste streams, extended producer responsibility (EPR) has evolved into an important framework for E-waste management and circular economy policies worldwide over the past thirty years. This policy has received increasing attention because of concerns regarding environmental pollution and resource depletion, as E-waste may contain heavy metals, such as mercury, cadmium, and lead, as well as valuable metals, including gold, silver, platinum, palladium, copper, and aluminum. In the developed East Asia region, Japan, South Korea (hereafter abbreviated as Korea), and Taiwan are renowned for their electronics industries and share similar socioeconomic and environmental characteristics, such as high population density, dependence on imported resources, and comparable levels of per capita national income. This review paper first provides the brief information on precious and valuable base metals derived from E-waste in urban waste. Furthermore, it presents a brief overview of the legal systems for urban waste management and compares urban mining from E-waste in Japan, Korea, and Taiwan. In this regard, the policies, regulations, and achievements related to urban waste management and E-waste recycling in East Asia, especially in Taiwan, are summarized and linked to increasing recycling rates for urban waste, including E-waste. Finally, the paper also examines two leading case studies in Taiwan, which focus on the recovery of precious metals from information and communication technology (ICT) products and valuable base metals from home electronic appliances, respectively. Full article

With the rapid construction of new power systems characterized by high renewable energy penetration, high power electronics integration, and high voltage levels, the insulation reliability of critical power equipment—including cable accessories, gas-insulated switchgear (GIS), and power electronic modules—faces unprecedented challenges. Field grading materials (FGM), as core functional media for adaptive electric field homogenization and insulation failure prevention, have emerged as a research hotspot spanning materials science, electrical engineering, and polymer engineering. Starting from the current research status of FGM, this review systematically summarizes filler optimization strategies, covering single fillers, hybrid fillers, trace co-fillers, and structural modification approaches. The applications of FGM in transmission cables, GIS, high-voltage electrical machines, and wide-bandgap power electronic modules are then elaborated in detail. Emphasis is placed on performance enhancement routes of FGM, particularly thermal conductivity improvement via constructing three-dimensional thermally conductive networks and intelligent early warning based on thermochromic materials. Finally, the existing bottlenecks of FGM are analyzed in terms of material stability, multi-physical field coupling adaptation, and engineering industrialization. Future development trends are prospected toward high-performance, multifunctional, intelligent, and engineering-oriented FGM. This review aims to provide theoretical references and technical support for the design and application of advanced FGM in new power systems. Full article

Background/Objectives: Hospital-Acquired Infections (HAI) represent one of the most frequent adverse events during care delivery, with the pediatric population (0–18 years) presenting unique vulnerabilities due to their developing immune systems, dependence on caregivers, and need for invasive devices. Despite the availability of general guidelines, existing high-level evidence is largely extrapolated from adult studies, and pediatric settings differ significantly in patient physiology and equipment size. This scoping review aims to map the key concepts, types of evidence, and research gaps related to strategies preventing HAI in pediatric patients. Methods: This scoping review will be conducted in accordance with the Joanna Briggs Institute (JBI) methodology and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews (PRISMA-ScR) guidelines. The Population, Concept, and Context (PCC) framework will be utilized. We will include any strategy, intervention, or protocol aimed at preventing HAI. A comprehensive search will be conducted across ten major electronic databases and grey literature sources. Two independent reviewers will screen titles, abstracts, and full texts, followed by data extraction using a standardized tool to categorize the interventions and key findings. Results: The findings will synthesize diverse practices into a usable format for clinical decision-makers and identify gaps where primary pediatric research is lacking. This consolidated data aims to guide resource allocation and assist hospital infection control committees in updating pediatric safety protocols. Conclusions: This scoping review will establish a comprehensive baseline of pediatric-specific HAI prevention strategies. The findings will inform evidence-based practice, identify critical research gaps, and guide future investigations in the prevention of pediatric infections in healthcare settings. Full article

This work investigates heat transfer experimentally and numerically within a ventilated cavity, both with and without an internal heat source, simulating a room with a person at the interior at 1:3 scale. This setup has applications in building energy systems, cooling of electronic equipment, solar energy collectors, etc. The experimental configuration consists of a cube in which the left vertical wall is subjected to a uniform heat flux, and the opposing wall is maintained at a constant temperature. A rectangular parallelepiped heat source was placed inside. The remaining walls are thermally insulated, and air is the thermal fluid. Air enters and exits through square ports on the top surface. Experimental temperature profiles were recorded at multiple depths and heights. Corresponding numerical results for temperature fields, flow patterns, turbulent viscosity, and turbulent kinetic energy were generated using the Ansys Fluent 18 CFD software, with six turbulence models assessed against experimental data under steady-state conditions. A key finding is that the Nusselt number and the convective heat transfer coefficients (average) for the hot wall remain negligibly affected by the incorporation or status (on/off) of a heat source at the interior of the cavity, the biggest temperature difference (experimental vs numerical) corresponds to the rkε model with 6.2% when there is no thermal source in the cavity and the lowest difference for the average convective heat transfer coefficient is with the rslrso model with 5.2%. Full article

Potassium sodium niobate (KNN) lead-free piezoelectric ceramics feature eco-friendliness and low density, coupled with superior high-frequency driving efficiency, albeit with inferior low-frequency performance. Conversely, Terfenol-D exhibits outstanding low-frequency driving capability but suffers from high density and poor high-frequency efficiency. This work proposes a ternary symmetric driving structure that integrates the complementary advantages of KNN and Terfenol-D, developing an underwater acoustic transducer with excellent lightweight design, low-frequency response, and broadband performance. The ternary symmetrically excited transducer maintains stable nodal planes across different operating frequencies and exhibits two distinct resonant frequencies. The vibration equation is analytically solved, and modal analysis is performed to clarify the evolution of the dual-resonance frequencies. A prototype transducer weighing 2.8 kg is fabricated and tested in an anechoic water tank. It delivers a maximum transmitting voltage response of 145 dB at 1.7 kHz with a broad operating bandwidth of 1–6 kHz. Compared with previously reported transducers, its weight is reduced by 26% to 93%. Benefiting from the double-ended radiation structure, the transducer yields a nearly omnidirectional radiation pattern. This ternary symmetrically excited transducer holds promising application prospects for underwater acoustic detection, communication, and navigation systems on unmanned underwater vehicle platforms. Full article

The increasing penetration of power electronic devices and distributed generation is significantly altering power quality conditions in low-voltage systems. While power quality assessment is commonly based on RMS currents, voltage quality indicators, and overall distortion metrics, these parameters may not fully reveal phase-selective harmonic behaviour in modern converter-dominated installations. This paper presents a measurement-based power quality assessment of a secondary school building equipped with a grid-connected photovoltaic (PV) system. A one-week monitoring campaign was conducted at the point of common coupling (PCC), capturing voltage, current, harmonic distortion, and power flow characteristics under real operating conditions. The results reveal pronounced phase-selective current harmonic distortion, with substantially elevated total harmonic distortion (THD_I) and total demand distortion (TDD) in one phase despite relatively balanced RMS current levels and acceptable voltage quality. The harmonic spectrum is dominated by low-order odd harmonics, whereas voltage distortion remains comparatively low and well balanced across phases. The study demonstrates that significant harmonic asymmetry may remain hidden in apparently balanced three-phase systems when assessment relies primarily on conventional RMS-based indicators. The findings highlight the importance of detailed current harmonic analysis and show that acceptable voltage quality does not necessarily imply acceptable current quality. The presented results provide measurement-based evidence of hidden harmonic asymmetry in modern low-voltage buildings and contribute to a better understanding of power quality challenges associated with nonlinear loads and distributed energy resources. Full article