Search Results (678)

Early and accurate detection of distributed bearing faults is essential to prevent equipment failures and reduce downtime in industrial environments. This study explores the optimal selection of input signal sources for high-accuracy distributed fault classification, employing wavelet transform and machine learning algorithms. The primary contribution of this work is to demonstrate that robust distributed bearing fault diagnosis can be achieved through optimal sensor fusion and wavelet-based feature engineering, without the need for deep learning or high-dimensional inputs. This approach provides interpretable, computationally efficient, and generalizable fault classification, setting it apart from most existing studies that rely on larger models or more extensive data. All experiments were conducted in a controlled laboratory environment across multiple loads and speeds. A comprehensive dataset, including three-axis vibration, stray magnetic flux, and two-phase current signals, was used to diagnose six distinct bearing fault conditions. The wavelet transform is applied to extract frequency-domain features, capturing intricate fault signatures. To identify the most effective input signal combinations, we systematically evaluated Random Forest, XGBoost, and Support Vector Machine (SVM) models. The analysis reveals that specific signal pairs significantly enhance classification accuracy. Notably, combining vibration signals with stray magnetic flux consistently achieved the highest performance across models, with Random Forest reaching perfect test accuracy (100%) and SVM showing robust results. These findings underscore the importance of optimal source selection and wavelet-transformed features for improving machine learning model performance in bearing fault classification tasks. While the results are promising, validation in real-world industrial settings is needed to fully assess the method’s practical reliability and impact on predictive maintenance systems. Full article

High-Voltage Direct Current (HVDC) systems are transforming the global energy landscape, distinguished by their efficiency, stability, and low impact on the electrical grid. One of the challenges of HVDC transmission line design is assessing the generated stray magnetic field, as it can have negative effects on human health and the environment. This study presents an analytical methodology for calculating the magnetic field density at any point along an HVDC line corridor. It considers the spatial configuration, the current per pole, and the location of the conductors. The equations allow for the calculation of the horizontal and vertical components of the field, as well as its total magnitude. A practical case study of a ±500 and ±600 kV HVDC two-pole transmission line is presented. The methodology was programmed in MATLAB^® version R2024a to calculate the magnetic field density, and the results are consistent with those obtained with the established methodology. The presented methodology can be applied to monopolar and two-pole HVDC overhead transmission lines, offering speed and accuracy. Full article

Mongolia’s rapidly expanding capital is encroaching on Bogd Khan Mountain, a UNESCO Biosphere Reserve and the oldest protected area in Eurasia. Gray wolves (Canis lupus) in this wildland–urban interface are locally near-threatened due to hunting, local beliefs, and human–wildlife conflict. In 2022 and 2023, we deployed 72 camera traps (11,539 trap nights) to investigate how wolves respond to overlapping pressures from free-ranging dogs, livestock, and human activity. Using a random habitat-stratified camera design and abundance modeling, we assessed diel activity and spatial co-occurrence. Wolves exhibited nocturnal and crepuscular activity, with the greatest temporal overlap with wild prey (wapiti: ∆⁴ = 0.73; Siberian roe deer: ∆⁴ = 0.79), moderate overlap with dogs (∆⁴ = 0.60) and horses (∆⁴ = 0.68), and minimal overlap with cattle (∆⁴ = 0.40) and people (∆⁴ = 0.43). Mean wolf abundance estimates ranged from λ = 0.91 (CI 95%, 0.05–1.77) in 2022 to λ = 1.52 (CI 95%, 0.44–3.53) in 2023. Wolves were more abundant at higher relative abundance of wild ungulates and in areas with more people. Wolves co-occurred with dogs at 11 sites and were more abundant in areas with a higher number of dogs. Our findings highlight the complex dynamics between wildlife, livestock, and human-associated disturbances at the wildland–urban interface, underscoring the need for integrated management strategies that address both ecological and human dimensions of conservation. Full article

The geostationary orbit (GEO), about 35,786 km above the Earth’s equator, hosts high-value satellites like communication, meteorological, and navigation ones. Real-time detection of geostationary orbit targets is crucial for orbital resource safety and satellite operation. Large field-of-view (FOV) telescopes can observe many such targets but face technical bottlenecks due to their optical systems, such as weak light-gathering capability, stellar interference, and complex stray light. This paper analyzes the apparent motion differences between stars and geostationary orbit targets based on the telescope’s staring mode. Stars move overall in images while GEO targets are relatively stationary. A minimum value stacking (Min-Stacking) method is proposed to suppress stars, improving GEO targets’ signal-to-noise ratio. With the global threshold segmentation algorithm, fast and accurate target extraction is achieved. Experiments show the method has high detection rates, overcomes interference, and features simplicity and real-time performance, with important application value. Full article

The proliferation of electrified rail systems has intensified stray current effects on chloride-induced corrosion in underground reinforced concrete (RC) structures, yet coupled mechanisms of stray current and chloride ingress—particularly in cracked concrete—remain insufficiently researched. This study establishes numerical models integrating chloride diffusion and electromigration to investigate stray current impacts on chloride transport in intact and cracked RC structures. Results reveal that stray current accelerates chloride ingress, with non-uniform electric fields causing 20–50% faster depassivation time of rebar than uniform fields at equivalent intensities. Cracked concrete exhibits 2–5 times shorter depassivation times of rebar compared to intact concrete, where crack depth–concrete cover thickness ratios exceeding 0.6 reduce service life by 40–60%. A novel deterioration coefficient β is formulated, demonstrating quadratic dependence on stray current voltage and linear correlation with cover thickness. These findings provide a predictive framework for durability assessment and corrosion mitigation in underground infrastructure exposed to synergistic chloride-stray current aggression. Full article

Capacitive-coupling non-contact voltage sensors face a key challenge: their probe-conductor coupling capacitance varies, making it hard to accurately determine the division ratio. This capacitance is influenced by factors like the conductor’s insulation material, radius, and relative position. To address this challenge, this paper proposes a sensor gain self-calibration method based on switching capacitors. This method obtains multiple sets of real-time measurement outputs by connecting and switching different standard capacitors in parallel with the sensor’s structural capacitance, and then simultaneously solves for the coupling capacitance and the voltage under test, thereby achieving on-site autonomous calibration of the sensor gain. To effectively suppress interference from stray electric fields in the surrounding space, a shielded coaxial probe structure and corresponding back-end processing circuitry were designed, significantly enhancing the system’s anti-interference capability. Finally, an experimental platform incorporating insulated conductors of various diameters was built to validate the method’s effectiveness. Within the 100–300 V power-frequency range, the reconstructed voltage amplitude shows a maximum relative error of 1.06% and a maximum phase error of 0.76°, and harmonics are measurable up to the 50th order. Under inter-phase electric field interference, the maximum relative error of the reconstructed voltage amplitude is 1.34%, demonstrating significant shielding effectiveness. For conductors with diameters ranging from 6 mm² to 35 mm², the measurement error is controlled within 1.57%. These results confirm the method’s strong environmental adaptability and broad applicability across different conductor diameters. Full article

A pulse generator capable of outputting quasi-square-wave pulses at the hundred-nanosecond scale is designed. With the development of high-power microwaves, the pulse flat-top is required to be more and more stable. However, at the hundred-nanosecond scale, an equal-value pulse-forming network is prone to being affected by stray parameters in the output waveform. To meet this requirement, a Marx generator and an anti-resonant network is used as the pulse boosting component and the pulse modulation component, respectively. Taking advantage of the anti-resonant network’s fewer sections and good modulation effect, the output waveform of the Marx generator is improved. The modulation ability of two-section and three-section modulation networks on waveforms, the output characteristics of two-section modulation networks, and the effect of stray parameters on the modulation network are explored. The experimental results show that both networks were able to achieve a quasi-square waveform of 100 kV on a 50 Ω load. Compared to the two-section network (165 ns pulse width, 41 ns rise time, 54.54% waveform flatness), the proposed three-section network achieves a pulse width of 185 ns with faster rise time (25 ns) and better waveform flatness (63.78%). Both topologies generate 100 kV quasi-square pulses on 50 Ω loads, with the three-section design demonstrating superior waveform control. In the repetition experiment, the pulse power source achieved stable operation at a repetition frequency of 20 Hz, and a quasi-square waveform with an output voltage of 100 kV was obtained. Finally, compared with previous studies, the modulated Marx generator based on an anti-resonant network has better waveform modulation effect and fewer network sections when generating a Square wave pulse of 100–200 ns. Full article

In the context of sustainable development, improving the durability of engineering materials and the service life of engineering projects is an important path to address engineering sustainability and low-carbon development. This study addresses the durability issues of steel fiber-reinforced cementitious materials (SFRCMs) under the combined action of stray current and chloride ions in metro engineering. Through simulated stray current-accelerated corrosion tests, combined with compressive strength tests and X-ray computed tomography (X-CT) analysis, the effects of steel fiber volume content (0.5%, 1.0%, 1.5%) and electrification duration (0–72 h) on the mechanical properties and corrosion mechanisms were systematically investigated. The results indicate that steel fiber content significantly influences corrosion rate and strength degradation. Specimens with 1.5% fiber content exhibited the highest initial compressive strength (58.43 MPa), but suffered a severe strength loss rate of 37.67% after 72 h of electrification. In contrast, specimens with 1.0% fiber content demonstrated balanced performance, achieving both high initial strength and superior corrosion resistance (19.66% strength loss after 72 h). X-CT analysis revealed that corrosion products initially filled pores during early stages but later induced microcracks in the matrix. Higher fiber content specimens exhibited increased large-pore ratios due to fiber agglomeration, accelerating chloride ion penetration. Furthermore, digital volume correlation (DVC) analysis demonstrated that steel fibers effectively dispersed loads and reduced stress concentration. However, post-corrosion fiber volume loss weakened their crack resistance capacity, highlighting the critical role of fiber integrity in structural durability. Full article

Star trackers are critical electro-optical devices used for satellite attitude determination, typically tested using Optical Ground Support Equipment (OGSE). Within the POR FESR 2014–2020 program (funded by Regione Toscana), we developed MINISTAR, a compact electro-optical prototype designed to generate synthetic star fields in apparent motion for realistic ground-based testing of star trackers. MINISTAR supports simultaneous testing of up to three units, assessing optical, electronic, and on-board software performance. Its reduced size and weight allow for direct integration on the satellite platform, enabling testing in assembled configurations. The system can simulate bright celestial bodies (Sun, Earth, Moon), user-defined objects, and disturbances such as cosmic rays and stray light. Radiometric and geometric calibrations were successfully validated in laboratory conditions. Under the PR FESR TOSCANA 2021–2027 initiative (also funded by Regione Toscana), the concept was further developed into STARLITE (STAR tracker LIght Test Equipment), a next-generation OGSE with a higher Technology Readiness Level (TRL). Based largely on commercial off-the-shelf (COTS) components, STARLITE targets commercial maturity and enhanced functionality, meeting the increasing demand for compact, high-fidelity OGSE systems for pre-launch verification of attitude sensors. This paper describes the working principles of a generic system, as well as its main characteristics and the early advancements enabling the transition from the initial MINISTAR prototype to the next-generation STARLITE system. Full article

The aim of the study was to analyze the impedance characteristics of the transmitting coil used in a system for AC magnetometry and the measurement of the Specific Absorption Rate (SAR) of magnetic nanoparticles. A theoretical relationship for the current distribution in a multilayer air-core coil was derived. The formulas for the coil’s stray capacitance were modified to account for additional spacing between layers, introduced to reduce the interlayer capacitance. The developed theory was applied to a two-layer air-core coil with an additional gap between the layers. The frequency dependence of the coil impedance was measured. The measurements confirmed an extension of the useful operating frequency range of the constructed coil. Full article

The Geostationary Interferometric Infrared Sounder (GIIRS) onboard the Fengyun-4B satellite plays a critical role in numerical weather prediction and extreme weather monitoring. To meet the requirements of quantitative remote sensing and high-precision operational applications for radiometric calibration accuracy, this study, based on pre-launch calibration experiments, conducts a novel modeling analysis of the coupling between stray radiation at the input side and the system’s nonlinearity, and proposes a correction method for nonlinear coupling errors. This method explicitly models and physically traces the calibration residuals caused by stray radiation introduced via non-nominal optical paths under the effect of system nonlinearity, which are related to the radiance of the observed target. Experimental results show that, within the brightness temperature range of 200–320 K, the calibration bias is reduced from approximately 0.7 to 0.3–0.4 K, with good consistency and stability observed across channels and pixels. Full article

Objective: To investigate public attitudes in New Zealand towards the euthanasia of dogs and cats and to explore the factors that influence these views. Materials and Methods: Data were collected through a nationwide online survey conducted in 2019 as part of the Furry Whānau Wellbeing research project. The survey included questions about pet euthanasia, and respondents were asked to indicate their level of agreement with various statements. Results: Of 2293 respondents to the 2019 New Zealand Pet Survey, the majority (n = 1756) opposed euthanasia for stray, unwanted, or financially burdensome pets (76.7%; 90.2% and 66.3% of these disagreed or strongly disagreed, respectively). In contrast, a slim majority (n = 1162) supported it for sick animals. Females were less likely to agree with euthanasia in most scenarios compared to males. Māori and New Zealand European respondents (n = 1790) showed higher levels of neutrality than other ethnicities regarding stray animals and lower levels of disagreement regarding financially constrained situations. Older respondents (65+) were more likely to support euthanasia for sick animals, while younger respondents (18–24) were less inclined. Higher education levels are correlated with increased neutrality towards euthanising stray animals and increased support for euthanising feral animals. Respondents with children were more likely to be neutral or to disagree with euthanasia in most scenarios. Those with rural upbringings were more accepting of euthanasia for stray and feral animals. A thematic analysis of 653 respondent comments revealed key themes: euthanasia was seen as complex and context-dependent, a humane last resort for suffering animals, but not for convenience. Respondents emphasised responsible pet ownership and a right to life, even for feral animals, advocating for alternatives such as trap–neuter–release. Conclusion: New Zealanders largely view euthanasia as an ethically acceptable option for terminally ill or suffering animals but reject it when driven by convenience or financial hardship. Attitudes vary across demographic groups, highlighting the need for culturally sensitive education and policy. The findings align with Sustainable Development Goal 3 (Good Health and Well-being) and support broader discussions on responsible pet ownership, ethical decision making, and animal welfare legislation. Full article

Most research on domestic dog (Canis familiaris) behavior has focused on pets with restricted movement. However, free-ranging dogs exist in diverse cultural contexts globally, and their interactions with humans are less understood. Tourists can facilitate unrestricted dog movement into wilderness areas, where they may negatively impact wildlife. This study investigated which stimuli—namely, voice, touch, or food—along with inherent factors (age, sex, sociability) motivate free-ranging dogs to follow a human stranger. We measured the distance (up to 600 m) of 129 free-ranging owned and stray dogs from three villages in southern Chile as they followed an experimenter who presented them one of the above stimuli or none (control). To evaluate the effect of dog sociability (i.e., positive versus stress-related or passive behaviors), we performed a 30 s socialization test (standing near the dog without interacting) before presenting a 10 s stimulus twice. We also tracked whether the dog was in the company of other dogs. Each focus dog was video-recorded and tested up to three times over five days. Generalized linear mixed-effects models revealed that the food stimulus significantly influenced dogs’ motivation to follow a stranger, as well as a high proportion of sociable behaviors directed towards humans and the company of other dogs present during the experiment. Juveniles tended to follow a stranger more than adults or seniors, but no effects were found for the dog’s sex, whether an owner was present, the repetition of trials, the location where the study was performed, or for individuals as a random variable. This research highlights that sociability as an inherent factor shapes dog–stranger interactions in free-ranging dogs when food is given. In the context of wildlife conservation, we recommend that managers promote awareness among local communities and tourists to avoid feeding dogs, especially in the context of outdoor activities close to wilderness. Full article

Livestock, poultry, and fisheries play an important economic role in Pakistan’s animal industry. The pet industry is also emerging and contributing to the country’s economy and people’s emotional well-being. This review provides insight into the current challenges and future directions of the animal industry in Pakistan. Livestock, poultry, and fisheries provide an economically beneficial source of milk, meat, and eggs; however, they face challenges such as disease outbreaks, antimicrobial resistance, climate change, natural disasters, and a lack of proper policies. Likewise, humans benefit from companion animals that provide emotional attachment. Moreover, the pet food market has also shown potential growth, contributing to the country’s economy. Due to the close association between animals and humans, both are at risk for infectious disease transmission. Challenges such as the lack of strong animal welfare laws and the increasing number of stray dogs and cats threaten human safety and that of other animals. We highlight current problems and additional approaches to the management of livestock, poultry, fisheries, and pets, which need to be addressed to further advance the animal industry in Pakistan. Full article

To enable accurate evaluation of satellite laser communication terminals under solar outage interference, this paper presents the design and implementation of a solar radiation simulation system targeting the 1540–1560 nm communication band. The system reconstructs co-propagating interference conditions through standardized and continuously tunable output, based on high irradiance and spectral uniformity. A compound beam homogenization structure—combining a multimode fiber and an apodizator—achieves 85.8% far-field uniformity over a 200 mm aperture. A power–spectrum co-optimization strategy is introduced for filter design, achieving a spectral matching degree of 78%. The system supports a tunable output from 2.5 to 130 mW with a 50× dynamic range and maintains power control accuracy within ±0.9%. To suppress internal background interference, a BRDF-based optical scattering model is established to trace primary and secondary stray light paths. Simulation results show that by maintaining the surface roughness of key mirrors below 2 nm and incorporating a U-shaped reflective light trap, stray light levels can be reduced to 5.13 × 10⁻¹² W, ensuring stable detection of a 10⁻¹⁰ W signal at a 10:1 signal-to-background ratio. Experimental validation confirms that the system can faithfully reproduce solar outage conditions within a ±3° field of view, achieving consistent performance in spectrum shaping, irradiance uniformity, and background suppression. The proposed platform provides a standardized and practical testbed for ground-based anti-interference assessment of optical communication terminals. Full article