Search Results (135)

The use of renewable energy sources instead of conventional ones, together with the development of efficient electricity storage solutions, represents a central objective of the transition to sustainable and resilient energy systems. In this context, two main development directions are the integration of hydrogen in the energy chain (Power-to-Gas) and the use of batteries, each with specific advantages and disadvantages, compared to internal combustion engines. The purpose of this work was to evaluate the dynamic response time of a hydrogen fuel cell model powered by green hydrogen, under conditions of sudden and instantaneous power demand, for its integration into wind-based renewable energy systems. Experimental research was carried out on an autonomous installation designed to operate continuously for an unlimited duration, simulating the integration of hydrogen produced from wind sources. The novelty consists of the application of an instrumental method for automatic measurement of the response time of a proton exchange membrane hydrogen fuel cell, based on the automatic acquisition and processing of measured electrical signals. The response time of the fuel cell was compared with that of an internal combustion engine based on the classic Carnot cycle, using a dedicated oscilloscope. The load connection time, the current and voltage variation as a function of time were recorded simultaneously. The results show that the response time of the fuel cell is relatively short (approximately 0.3 ms), much lower than that of the internal combustion engine (0.7 s), being of the order of about 2333 times smaller. In conclusion, the hydrogen fuel cell can be effectively integrated into renewable energy systems for the role of an uninterruptible power supply, with an exceptionally fast dynamic response, suitable for applications in regulating and supporting wind-powered networks. Full article

As the demand for digital storage capacity continues to grow, bit-patterned magnetic recording (BPMR) has emerged as a promising technology to overcome the superparamagnetic limit of conventional recording methods. Nevertheless, the extremely close spacing of magnetic islands in BPMR can result in significant signal corruption, particularly due to inter-track interference. This paper presents robust signal-processing schemes for a two-reader, three-track detection system in a staggered BPMR configuration to address these challenges. The first proposed method employs a sum-soft-information technique, which combines log-likelihood ratios from two detectors to maximize mutual information. This approach significantly improves the reliability of middle-track detection. We also propose the inter-track interference subtraction technique, in which the highly reliable data recovered from the middle track are used to reconstruct the interference signal, which is then subtracted from the upper and lower tracks using an optimized weighting factor. Simulation results at an areal density of 3.0 Tb/in² demonstrate that an optimized weighting factor of 1.78 effectively cancels interference. Moreover, the results indicate that our proposed scheme achieves a bit-error rate (BER) comparable to that of the three-reader, one-track detection BPMR systems. Furthermore, our method also demonstrates a lower BER for both adjacent tracks when compared to the conventional single-reader, two-track reading system, even in the presence of 10% media noise. Full article

Respiration rate (RR) is a key physiological indicator of health, stress, and thermoregulatory load in dairy cattle, yet continuous RR monitoring under commercial farm conditions remains challenging. In this Technical Note, we present a non-invasive clip-on nose ring device for continuous respiration monitoring based on acoustic recording directly at the nostril. The device integrates a MEMS microphone, embedded electronics, battery, and removable storage in a sealed, mechanically robust housing suitable for real-world barn environments. The system was deployed on five dairy cows under commercial farm conditions, enabling repeated multi-day recordings over several weeks. The respiration rate was extracted offline from raw audio using a deterministic signal-processing pipeline based on multiscale periodicity detection. Algorithm-derived RR estimates were evaluated against manually annotated breath events. Using 10-min rolling median values, the algorithm achieved a mean absolute error (MAE) of 1.47 breaths per minute (bpm), a root mean square error (RMSE) of 1.92 bpm, and a high correlation with reference values (r = 0.98, R² = 0.96). In addition to short-term accuracy, the system enabled stable multi-day monitoring. Group-level analysis across all five animals revealed a clear diurnal respiration pattern over multiple consecutive days, with lower RR during nighttime and higher RR during daytime summer conditions, without signs of a baseline drift. These results demonstrate the feasibility of continuous, long-term respiration monitoring in dairy cattle using an audio-based clip-on nose ring device and provide a practical foundation for longitudinal (multi-day, within-animal) RR assessment under commercial farm conditions, with potential for future extensions towards advanced respiratory health monitoring. While the system demonstrated stable performance under summer farm conditions, validation under extreme heat-stress environments and larger animal cohorts is required for comprehensive population-level assessment. Full article

Submarine gas emissions represent a key expression of fluid migration processes in volcanic and hydrothermal marine environments and provide valuable analogues for monitoring strategies relevant to sub-seabed carbon storage. This study investigates the feasibility of using marine Distributed Acoustic Sensing (DAS) to detect natural CO₂ bubble emissions in a shallow-water setting offshore Panarea (Aeolian Islands, Italy). A 1.1 km armored fiber-optic cable was deployed on the seabed and interrogated using two different DAS systems to acquire continuous passive acoustic data. The DAS recordings were complemented by controlled gas releases from scuba tanks to provide reference signals, as well as by independent high-resolution boomer seismic survey and side-scan sonar imaging to characterize the shallow subsurface and seabed morphology. The results show that DAS is sensitive to acoustic signals associated with both artificial and natural bubble emissions, despite the complex acoustic conditions typical of shallow marine environments. The integration of passive DAS monitoring with independent geophysical observations provides a robust framework for interpreting gas-related signals and seabed processes. These findings demonstrate that marine DAS represents a promising geophysical tool for monitoring of submarine volcanic–hydrothermal systems and offers important insights for the development of sub-seabed CO₂ leakage detection in offshore CCS contexts. Full article

Historic cities face a dual challenge of managing waterlogging risks while adhering to strict preservation constraints. Traditional drainage upgrades often require extensive excavation, threatening cultural heritage. This study establishes a quantitative assessment framework for the historic urban district of City B using a 1D-2D-coupled hydrodynamic model (InfoWorks ICM). The model was calibrated using continuous monitoring data, achieving a Nash–Sutcliffe Efficiency (NSE) of 0.91. Its spatial accuracy was subsequently validated against historical waterlogging records, showing a strong consistency between simulated flood-prone areas and observed flood locations. We simulated waterlogging distribution under rainfall events with return periods of 0.5 to 5 years. Results reveal two key deficiencies in the current drainage system under a 0.5-year return period storm event. Firstly, 75.3% of the pipe segments are hydraulically overloaded, failing to meet the design standard. Secondly, this widespread network overload contributes to surface waterlogging, with 9.58 ha (1.80% of the total area) being waterlogged. We evaluated three strategies: Low Impact Development (LID), underground storage tanks, and intercepting sewers. A hybrid grey-green infrastructure (HGGI) system was proposed, integrating source reduction and terminal storage. The HGGI system reduced waterlogged areas by 83.58% (0.5-year event) and 64.87% (5-year event), outperforming single measures. Crucially, this hybrid system achieves minimal intervention in historic street patterns through trenchless construction for intercepting sewers, decentralized LID layout and underground storage tanks, avoiding large-scale road excavation while enhancing flood resilience. This study demonstrates that hybrid strategies can effectively balance flood resilience with environmental and cultural preservation in high-density historic districts. Full article

As a crucial pillar industry in the country, the automotive industry continues to evolve with the increasing number of vehicles in operation, leading to a continual rise in the need for aftermarket parts and repair services. Fluctuations in automotive spare part requirements are influenced by various complex factors, which significantly impact production costs. The intermittent distribution of such requirements and strict limitations highlights the importance of automotive spare part management to enhance production efficiency and reduce costs. To improve demand forecasting accuracy, this study summarizes and synthesizes trends in automotive spare parts; proposes a tree-based machine learning forecasting model, based on a two-stage random forest (RF) structure that separately models demand occurrence probability and conditional demand size; and compares the outcomes with benchmarks to validate model effectiveness. The empirical study is conducted using an industrial dataset consisting of monthly demand records for approximately 2500 spare parts over a four-year period. This forecasting approach enables companies to rationalize inventory storage, ensure the quality of automotive repairs, and elevate service standards. Simultaneously, by improving the efficiency of inventory planning and allocation decisions, companies can enhance the quality of after-sales services, reduce inventory costs, and maximize the value of the automotive industry chain. Through reducing spare parts wastage and further lowering enterprise costs and industrial emissions, companies can achieve the goals of automotive supply chain resilience. Notably, this study focuses on automotive spare parts management and provides a feasible, reliable, and interpretable forecasting solution for automotive manufacturers to address intermittent demand challenges in spare parts management. Full article

This paper examines the use of organic-based materials to monitor levels of corrosivity in indoor microclimate environments, which include proximity to artworks, artworks in display cases, and, in particular, in microclimate frames for paintings. It reviews research conducted within four EU-funded projects: Environmental Research for Art Preservation (ERA), Microclimate Indoor Monitoring in Cultural Heritage Preservation (MIMIC), Improved Protection of Paintings during Exhibition and Storage (PROPAINT), and Measurement, Effect Assessment, and Mitigation of Pollutant Impact on Movable Cultural Assets—Innovative Research for Market Transfer (MEMORI). The ERA project introduced the use of egg tempera paint dosimeters to assess levels of corrosivity in proximity to artworks. A multi-analytical approach was employed to evaluate chemical changes in the dosimeters, enabling risk assessment, exemplified by samples exposed at Sandham Memorial Chapel, Hampshire, UK. Building on this, in the MIMIC project, coated piezoelectric quartz crystals (egg tempera and resin mastic), a varnish commonly used by artists, were exposed at a number of sites together with the same coatings on steel strips. These were further employed in the PROPAINT project together with some continuous monitoring prototypes to investigate the nature of microclimates both within specially designed mc-paint frames and in the surrounding room environments. This paper presents Fourier Transform Infrared Spectroscopy (FTIR) and Dynamic Mechanical Analysis (DMA) from these exposures, together with environmental data recorded during the monitoring period and information on frame types used. Some correlation was found between FTIR, DMA, and environmental data. The findings reveal that changes in the physico–chemical properties measured by the techniques correlate with the environmental conditions. It also points to the possibility of using FTIR to monitor chemical changes in exposed coated strips. Additional data from the MEMORI project of similar exposures but including dammar and Regalrez 1094 varnish are also presented. Full article

The impact of climate change on marine bivalves, particularly on their reproductive processes, is a current issue of concern. The aim of this study was to investigate how seawater temperatures influenced the gonadal development and overall condition of the grooved carpet shell clam (Ruditapes decussatus, Linnaeus, 1758) population in the Baldaio lagoon (N.W. Spain) over the last 20 years. Adult clams were collected, and biometric, histological, and biochemical analyses were performed. Gonadal development phases were assessed, several condition indices were calculated, water temperatures were recorded, and statistical analyses were carried out. Results indicated variations in reproductive timing, including changes in gonadal maturation, an earlier spawning period, and prolonged maturation phases, which contrasted with previous reproductive patterns described for this species. These findings coincided with thermal changes in the lagoon, where mean minimum temperatures increased and maximum temperatures decreased, and the annual thermal range was reduced in comparison with historical data (1998–1999). Biochemical composition and condition indices also reflected variations linked to temperature fluctuations, suggesting that warmer water temperatures may alter energy storage and reproduction. This highlights the importance of continuous environmental monitoring to better understand the effects of climate change on clam populations and to improve management strategies that could help to restore natural R. decussatus populations. Full article

Background: Integrating Radio Frequency Identification (RFID) technology into storage areas within the wiring harness manufacturing industry enables real-time component traceability and supports the implementation of fully automated inventory processes. While RFID systems provide continuous data regarding component type, quantity, and location, periodic inventory validation is still required to verify and correct records in the warehouse management system. Methods: This study examines the feasibility of passive ultra-high-frequency (UHF) RFID technology for automatic inventory management in a components warehouse. It also reviews relevant scientific literature on autonomous RFID signal measurement and Synthetic Aperture Radar (SAR)-based localization methods, which are subsequently adapted for inventory applications. An experimental setup is developed to characterize the reading field, hysteresis effects, and the influence of distance and tag orientation on detection performance. Results: The findings indicate that RFID-based automatic inventory is achievable with high accuracy and stability, especially when tag trajectories correspond to areas of high detection probability and antenna polarization is optimally configured. Conclusions: The proposed RFID-based system can be implemented with minimal hardware changes and low investment, thereby improving stock accuracy, traceability, and operational efficiency in automotive component logistics. Full article

The paper continues the authors’ efforts to characterize and control the shape memory effect (SME) occurring in 3D printed specimens of recycled polyethylene terephthalate (rPET) and polyethylene terephthalate glycol (rPETG). Lamellar and “dog-bone” configuration specimens were 3D printed in the form of stratified composites with five different rPET/rPETG ratios, 100:0, 60:40, 50:50, 40:60, and 0:100, and two different angles between the specimen’s axis and the deposition direction, 0° and 45°. The lamellar specimens were used for: (i) free-recovery SME-investigating experiments, which monitored the variation of the displacement, of the free end of specimens which were bent at room temperature (RT), vs. temperature, during heating, (ii) differential scanning calorimetry (DSC), which emphasized heat flow variation vs. temperature, during glass transition and (iii) dynamic mechanical analysis (DMA), which recorded storage modulus vs. temperature in the glass transition interval. Dog-bone specimens were subjected to tensile failure and loading-unloading tests, performed at RT. The broken gauges were metallized with an Au layer and analyzed by scanning electron microscopy (SEM). The results showed that the specimens printed with 0° raster developed larger free-recovery SME strokes, the largest one corresponding to the specimen with rPET/rPETG = 40:60, which experienced the highest storage modulus increase, 872 MPa, and maximum value, 1818 MPa, during heating. The straight lamellar composite specimens experienced a supplementary shape recovery when bent at RT and heated, in such a way that their upper surface became concave, at the end of heating. Most of the specimens 3D printed at 0° raster developed stress failure plateaus, which were associated with the formation of delamination areas on SEM fractographs, while the specimens printed with 45° raster angle experienced necking failures, associated with the formation of crazing areas. The results suggested that 3D printed stratified rPET-rPETG composites, with dedicated spatial configurations, have the potential to serve as executive elements of light actuators for low-temperature operation. Full article

This paper presents the design, modeling and experimental validation of an on-grid photovoltaic system with self-consumption, sized for the sustainable supply of a water pumping station. The system, composed of 68 photovoltaic panels, uses an architecture based on a Boost DC-DC converter controlled by the Perturb and Observe algorithm, raising the operating voltage to a high-voltage DC bus to maximize the conversion efficiency. The study integrates dynamic performance analysis through simulations in the Simulink environment, testing the stability of the DC bus under sudden irradiance shocks, with rigorous experimental validation based on field production data. The simulation results, which indicate a peak DC power of approximately 34 kW, are confirmed by real monitoring data that records a maximum of 35 kW, the error being justified by the high efficiency of the panels and system losses. Long-term validation, carried out over three years of operation (2023–2025), demonstrates the reliability of the technical solution, with the system generating a total of 124.68 MWh. The analysis of energy flows highlights a degree of self-consumption of 60.08%, while the absence of chemical storage is compensated for by injecting the surplus of 49.78 MWh into the national grid, which is used as an energy buffer. The paper demonstrates that using the grid to balance night-time or meteorological deficits, in combination with a stabilized DC bus, represents an optimal technical-economic solution for critical pumping infrastructures, eliminating the maintenance costs of the accumulators and ensuring continuous operation. Full article

Based on GRACE RL06 data, this study reconstructs a monthly Terrestrial Water Storage Anomaly (TWSA) series in Shandong Province (2003–2024) using Singular Spectrum Analysis (SSA) and derives Groundwater Storage Anomaly (GWSA) via the water balance equation. The spatiotemporal evolution characteristics of GWSA were systematically examined, and the relative contributions of climatic factors and human activities to groundwater storage changes were quantitatively assessed, with the aim of contributing to the development, utilization, and protection of groundwater in Shandong Province. The results indicate that temporally, GWSA in Shandong Province exhibited a statistically significant decreasing trend at a rate of −8.45 mm/a (p < 0.01). The maximum GWSA value of 17.15 mm was recorded in 2006, while the Mann–Kendall abrupt change-point analysis identified 2013 as a significant transition point. Following this abrupt change, GWSA demonstrated a persistent decline, reaching the minimum annual average of −225.78 mm in 2020. Although moderate recovery was observed after 2020, GWSA values remained substantially lower than those in the pre-abrupt change period. Seasonal analysis revealed a distinct “higher in autumn and lower in spring” pattern, with the most pronounced fluctuations occurring in summer and the most stable conditions in winter. Spatially, approximately 99.1% of the study area showed significant decreasing trends, displaying a clear east–west gradient with more severe depletion in inland regions compared to relatively stable coastal areas. Crucially, human activities emerged as the dominant driving factor, with an average contribution rate of 86.11% during 2003–2024. The areal proportion where human activities served as the decisive factor (contribution rate > 80%) increased dramatically to 99.58%. Furthermore, the impact of human activities demonstrated bidirectional characteristics, transitioning from negative influences during the depletion phase to positive contributions promoting groundwater recovery in recent years. At present, the GWSA in Shandong Province is expected to continue declining in the future, with an overall downward trend. Countermeasures must be implemented promptly. Full article

The study presents an upgraded design and the results of experimental investigations of a solid-propellant pulsed plasma thruster (PPT) in which graphite simultaneously serves as both the propellant and the ignition element. The proposed configuration comprises a planar parallel system of copper electrodes and a graphite initiating electrode equipped with an electromagnetic discharge-triggering mechanism. Experimental tests were conducted under vacuum conditions of approximately 10⁻⁵ Torr at an energy-storage capacitor voltage of 800–1400 V. Discharge current amplitudes of up to 3.16 kA were recorded at a single-pulse energy of up to 4.41 J. The measured impulse bit was about 17.1 μN $·$s, and the plasma jet exhaust velocity reached 11.1 km/s. Spectroscopic analysis of the plasma confirmed the presence of characteristic carbon emission lines, thereby indicating the active participation of the graphite propellant in the formation of the plasma plume. The present work continues previous research on PPTs with graphite electrodes and is aimed at further miniaturization of the earlier developed design. The primary objective of the study is the experimental validation of the proposed discharge concept in a planar parallel electrode configuration while preserving the key thrust and energy performance characteristics of the thruster. Full article

Carbon dioxide capture and storage (CCS) is a technology that can be used to reduce carbon dioxide (CO₂) emissions generated by both natural and anthropogenic industrial processes, particularly petroleum production. To mimic and investigate the effects of CO₂ leakage that may result from CCS, the acute toxicity of seawater acidification induced by continuous CO₂ injection was studied in Asian seabass (Lates calcarifer) fry under static bioassay conditions. Fry (0.828 ± 0.22 g) were exposed to seawater with different pH levels (5.5, 6.0, 6.5, 7.5, and 8.3). Rapid and 100% mortality within 15 min was observed in the pH 5.5 exposure group, while mortality rates ranging from 10.00–41.67% were recorded at 6–96 h in the pH 6.0 exposure group; no mortality was noted in the other pH exposure groups. According to these mortality data, the median lethal concentration at 96 h (96 h LC₅₀) was determined to be a pH of 5.884. Interestingly, after exposure to seawater with pH levels of 5.5 and 6.0, histopathological alterations in the skin, gills, trunk kidney and liver were evident. Additionally, some water quality parameters, especially dissolved oxygen (DO) levels, alkalinity, ammonia levels, and nitrite levels, vary depending on the pH. To further investigate the effects of seawater with pH levels of 8.3 and 5.884 (96 h LC₅₀) and 6.5 (10% safety level) on health status, immune responses and disease susceptibility, fingerling fish (21.25 ± 3.89 g) were studied. Unexpectedly, fish exposed to seawater with a pH of 5.884 rapidly lost muscle control and gradually died, reaching 100% mortality within 24 h, and all response analyses were aborted. Interestingly, with the exception of hematocrit and some immune parameters, various serum innate immune indices, blood biochemistry parameters and immune-related gene expression patterns were similar in fish exposed to seawater with pH levels of 8.3 and 6.5. Additionally, fish were challenged with 0 (control), 1 × 10⁷ and 1 × 10⁹ CFU/mL Vibrio vulnificus, and fish in seawater with a pH level of 6.5 showed a higher sensitivity to 1 × 10⁹ CFU/mL Vibrio vulnificus than fish in seawater with a pH level of 8.3, with mortality rates of 71.24% and 25.44%, respectively (p < 0.05). These findings enhance the understanding of the toxicity effects of seawater acidification caused by CO₂, which will be useful for further assessing the site-specific effects of CCS projects. Full article

The rapid increase in global data generation has intensified the demand for magnetic storage systems with substantially higher areal density. Double-layer bit-patterned media recording (DLBPMR), which integrates the benefits of bit-patterned media recording (BPMR) and double-layer magnetic recording (DLMR), provides a promising pathway by combining nanoscale patterned islands with multilayer recording structures. However, severe two-dimensional intersymbol interference (ISI) within each layer, together with interlayer interference (ILI) between stacked layers, continues to present significant challenges for reliable data detection. To address these issues, this work investigates and advances the structure of DLMR to improve signal separation and recovery. In particular, we emphasize that detection plays a crucial role in mitigating both ISI and ILI. Accordingly, we propose a maximum a posteriori (MAP) detection scheme derived for a newly developed generalized two-layer partial-response (PR) model that accurately characterizes intra-layer ISI and cross-layer interference coupling. A parallel detection architecture is designed and employed for the upper and lower layers of the DLMR system, enabling the exchange of extrinsic information and enhancing MAP detection performance. Simulation results demonstrate that the proposed PR modeling and MAP-based detection framework achieves significant bit error rate (BER) improvements over existing detection methods, highlighting its strong potential for next-generation ultra-high-density DLBPMR systems. Full article