Search Results (16,735)

This research paper proposes a framework utilizing multicriteria tools for optimal site selection of photovoltaic solar farms. A comparative analysis was conducted using three quantitative methods—CRITIC (criteria importance through intercriteria correlation), PCA (principal component analysis), and entropy—to obtain the weights for the selection process. The evaluation considered environmental, demographic, financial, meteorological, and performance system criteria. TOPSIS (technique for order preference by similarity to ideal solution) was employed to rank the alternatives based on their proximity to the ideal positive solution and distance from the ideal negative solution. The capital cities of the seven departments in the Colombian Caribbean region were selected for the assessment, characterized by high annual solar radiation, to evaluate the suitability of the proposed decision-making framework. The results demonstrated that Barranquilla consistently ranked in the top two across all methods, indicating its strong performance. Cartagena, for instance, fluctuated between first and third place, showing some stability but still influenced by the method used. In contrast, Sincelejo consistently ranked among the lowest positions. A sensitivity analysis with equal weight distribution confirmed the top-performing cities, though it also highlighted that the weight assignment method impacted the final rankings. Choosing the appropriate method for weight calculation depended on factors such as the diversity and interdependence of criteria, the availability of reliable data, and the desired sensitivity of the results. For instance, CRITIC captured inter-criteria correlation, while PCA focused on reducing dimensionality, and entropy emphasized the variability of information. Full article

The increasing demand to harness offshore wind resources has pushed offshore wind turbines into deeper waters, making floating platforms more economically feasible than bottom-fixed ones. When the incident wind and wave forces act on the floating wind turbine, the floating platform will experience oscillations around its equilibrium position in six degrees of freedom (DOFs). Significant floater motions can affect the aerodynamic power output, increase the failure risk, and even shorten the operational lifetime, especially under a harsh offshore environment. To improve the dynamic behavior of the floating platform, this research designed a heave plate for an OC4-Deepcwind wind turbine. The dynamic performance of the wind turbine was specifically investigated based on a series of wave-basin model tests, including free decay tests, regular wave tests, and irregular wave with steady wind tests. The results show that the heave plate increases damping in heave and pitch motions. The weakening effect on the heave and pitch motion is obvious in the wave period of 15–20 s and 20–27 s, respectively. However, the arrangement of the heave plate may exacerbate the fluctuation of the force and moment at the bottom of the tower. Full article

Meniere’s disease (MD) is a chronic inner ear disorder characterized by tinnitus, ear fullness, episodic vertigo, and fluctuating hearing loss, which significantly impacts quality of life and poses management challenges. Recent evidence suggests that upper respiratory infections (URIs) may contribute to MD’s onset. This study examines the potential link between URIs and MD using data from the Korean National Health Insurance Service-National Sample Cohort (2002–2019). We analyzed 19,721 individuals with MD and 78,884 matched controls, adjusting for demographic factors and comorbidities using propensity score matching. Our results showed that individuals with a URI within one year prior to the index date exhibited a 2.01-fold greater likelihood of developing MD (95% confidence interval [CI] = 1.91–2.11, p < 0.001), while those with URIs within two years demonstrated a 1.54-fold higher probability (95% CI = 1.50–1.59, p < 0.001). Furthermore, we found that even remote URIs occurring up to two years before the index date significantly increased the risk of developing MD, underscoring the need for long-term patient follow-up. Overall, our study suggests that individuals with a history of URI may have an elevated risk of developing MD over multiple time frames, regardless of demographic or health profiles. Full article

The increasing frequency and severity of climate variability poses substantial challenges to the sustainability and reliability of transportation infrastructure worldwide. Transportation systems, vital to economic and social activities, are highly vulnerable to extreme weather, sea-level rise, and temperature fluctuations, which can disrupt their structural integrity, operational efficiency, and maintenance needs. The aim of this study is to explore the scholarly landscape concerning the effects of climate variability on transportation systems, analyzing 23 years of scientific publications to assess research trends. Utilizing bibliometric methods, this analysis synthesizes data from numerous scientific publications to identify key trends, research hotspots, influential authors, and collaborative networks within this domain. This study highlights the growing acknowledgment of climate variability as a crucial factor affecting the design, maintenance, and operational resilience of transportation infrastructure. Key findings indicate a notable increase in research over the last decade, with a strong focus on the effects of extreme weather events, sea-level rise, and temperature changes. The analysis also shows a multidisciplinary approach, incorporating perspectives from civil engineering, environmental science, and policy studies. This comprehensive overview serves as a foundational resource for researchers and policymakers, aiming to enhance the adaptive capacity of transportation systems to climate variability through informed decision-making and strategic planning. Full article

Radial gate, a spatial frame structure, is the key factor to control water discharge in dam structure and storm surge barriers. However, the fluid-induced vibration (FIV) problem always occurs owing to fluctuation loads exerted on the gate, threatening the safety of hydropower stations. In this work, two fluid–structure interaction (FSI) modal analysis methods—the coupled acoustics–structure method and the added-mass method—are provided. Further, a comprehensive investigation on the vibration characteristics of the spatial radial gate, considering spatial structural characteristics and the FSI effect, is conducted. The numerical results revealed that the feasibility of the proposed coupled acoustics–structure method in analyzing FSI modal analysis was demonstrated; moreover, a reasonable length of the fluid domain in front of the skinplate existed for efficient computation. Meanwhile, through the added-mass method, the rational added-mass discount factor of hydrodynamic loads obtained from the Westergaard formula was provided. The FSI effect induced whole-gate rotation vibration streamwise around trunnion pins, significantly reducing the gate’s fundamental vibration frequency. In addition, three typical dynamic-instability vibration patterns of radial gates were presented. These patterns were affected by spatial structural characteristics and FSI. It was demonstrated that the struts and skinplate coupled bending–torsional vibration would cause the radial gate frame structure to fail catastrophically. The proposed insights can provide guidelines of vibration characteristics analysis of the radial gate submerged in flow water in reservoir and storm surge barriers. Full article

Jeju Island, located in the northern East China Sea, is experiencing a rapid rise in water temperature due to climate change. This has led to the increased activity of subtropical species and extreme fluctuations in coastal ecosystems, such as macroalgal blooms and coral bleaching. Additionally, the region is experiencing more frequent and intense typhoons. This study investigated the green tides caused by Ulva, particularly Ulva ohnoi, a subtropical species, and the effects of typhoons on these blooms through photographic analysis of the Jeju coastline. The study area was consistently covered by Ulva species every August from 2020 to 2022. Super typhoons struck Jeju Island every September during the study period, with wind speeds exceeding 20 m/s. In 2020 and 2022, the green tides largely dissipated following the typhoons. This ironic outcome highlights how climate-driven increases in subtropical Ulva biomass are being mitigated by the increasing frequency of super typhoons. However, despite the impact of super typhoon Chanthu in September 2021, there was no significant reduction in the Ulva bloom area. This anomaly may be attributable to the dominant easterly wind system in 2021, as the study area faces east, preventing the typhoon from influencing the distribution of Ulva blooms. These findings suggest that the wind intensity and direction of annual typhoons play a critical role in determining the resolution of green tide outbreaks. Full article

This review article delves into the intriguing phenomenon of low-temperature thermochromism, whereby materials change color in response to temperature variations, with a particular focus on its applications in temperature-sensitive fields like medical storage. By closely examining thermochromic materials, this article highlights their potential to offer innovative solutions for monitoring and preserving thermolabile products that require strict temperature control. This leads to a special emphasis on polydiacetylenes (PDAs), a class of conjugated polymers with unique low-temperature thermochromic properties, positioning them as promising candidates for reliable temperature indicators. This article then explores the underlying mechanisms for fine-tuning the thermochromic behavior of PDAs, particularly discussing recent advancements in PDA design, such as structural alterations of monomers to achieve low-temperature thermochromism. These modifications, influenced by factors like side-chain length, hydrogen-bonding interactions, and the use of copolymers, are intended to result in irreversible color transitions at specific low temperatures, which is crucial to maintaining the integrity of thermally sensitive products. Finally, this article discusses the potential applications of PDAs as thermochromic sensors in tissue biobanking, where their ability to provide visual indications of temperature fluctuations could significantly enhance the monitoring and management of biological samples. Full article

This exploratory study investigates changes in the autonomic cardiac system of young analog astronauts in a hostile, confined, and isolated environment. It uses linear and nonlinear indices of heart rate variability (HRV) during a Mars analog mission to assess how HRV varies under day and night stressors. This study is guided by the hypothesis that significant HRV changes occur based on adaptation days, aiming to offer insights into autonomic nervous system (ANS) adaptation to environmental stressors. Over five days in August 2022, five analog astronauts faced adverse conditions in the Mojave Desert, simulating Martian conditions. Electrocardiograms were recorded daily for five minutes during morning and evening sessions to extract short-term RR time series. HRV parameters were analyzed using both time- and frequency-domain indices and nonlinear measures. Significant differences in HRV parameters across days highlight the mission environment’s impact on autonomic cardiac function. Morning measurements showed significant changes in average RR intervals and heart rate, indicating ANS adaptation. Nonlinear indices such as detrended fluctuation analysis and approximate entropy also showed significant differences, reflecting shifts in autonomic function. The Borg scale indicated reduced perceived exertion over time, aligning with HRV changes. Increased vagal activity during Mars analog adaptation under confinement/isolation may be crucial for cardiovascular adaptation and survival in future space flights. Full article

Due to real-time fluctuations in wind farm output, large-scale renewable energy (RE) generation poses significant challenges to power system stability. To address this issue, this paper proposes a deep reinforcement learning (DRL)-based electric hydrogen hybrid storage (EHHS) strategy to mitigate wind power fluctuations (WPFs). First, a wavelet packet power decomposition algorithm based on variable frequency entropy improvement is proposed. This algorithm characterizes the energy characteristics of the original wind power in different frequency bands. Second, to minimize WPF and the comprehensive operating cost of EHHS, an optimization model for suppressing wind power in the integrated power and hydrogen system (IPHS) is constructed. Next, considering the real-time and stochastic characteristics of wind power, the wind power smoothing model is transformed into a Markov decision process. A modified proximal policy optimization (MPPO) based on wind power deviation is proposed for training and solving. Based on the DRL agent’s real-time perception of wind power energy characteristics and the IPHS operation status, a WPF smoothing strategy is formulated. Finally, a numerical analysis based on a specific wind farm is conducted. The simulation results based on MATLAB R2021b show that the proposed strategy effectively suppresses WPF and demonstrates excellent convergence stability. The comprehensive performance of the MPPO is improved by 21.25% compared with the proximal policy optimization (PPO) and 42.52% compared with MPPO. Full article

LSTM (long short-term memory) networks have been proven effective in processing stock data. However, the stability of LSTM is poor, it is greatly affected by data fluctuations, and it is weak in capturing long-term dependencies in sequential data. BiLSTM (bidirectional LSTM) has alleviated this issue to some extent; however, due to the inefficiency of information transmission within the LSTM units themselves, the generalization performance and accuracy of BiLSTM is still not very satisfactory. To address this problem, this paper improves LSTM units on the basis of traditional BiLSTM and proposes a He-BiLSTM (heterogeneous bidirectional LSTM) with a corresponding backpropagation algorithm. The parameters in He-BiLSTM are updated using the Adam gradient descent method. Experimental results show that compared to BiLSTM, He-BiLSTM has further improved in terms of accuracy, robustness, and generalization performance. Full article

The plasma bulk velocity is one of the key parameters describing the behavior of a plasma jet and is relevant for applications such as plasma spraying or electric propulsion. Therefore, different measurement techniques to determine the velocity were developed in the past. This paper presents a novel, non-invasive method for spatially resolved velocity measurements. The method is based on tracking of characteristic features in tomographic reconstructions of the plasma plume. A high-speed image recording system combined with tomographic acquisition is therefore the backbone of this method. The proposed setup captures the object under study from six different directions at a frame rate up to one million frames per second, providing high spatial and temporal resolution. The tomographic reconstructions are then calculated using the ART algorithm to track features in the plasma fluctuations, from which the bulk velocity is determined. The setup was tested with a DC plasma torch operated at reduced pressures in the range of tens of millibars. For the analyzed parameters, the axial velocity reached a maximum of 1061 m/s at a distance of three centimeters from the plasma torch exit and decreased to 919 m/s further downstream at a distance of seven centimeters, which is in good accordance with previous work. Therefore, the proposed diagnostic method can serve as a non-invasive alternative to velocity measurements, providing additional information in the form of a 3D model of the plasma bulk. Full article

The power battery configuration of an extended-range electric vehicle directly affects the overall performance of the vehicle. Optimization of the output voltage of the power battery can improve the overall power and economy of the vehicle to ensure its safe operation. Factors affecting the output voltage of power batteries under different operating conditions, such as nominal voltage and the number of series and parallel connections of the battery cells, have been studied. This study uses AVL Cruise to establish an overall model of an extended-range electric vehicle to simulate the output voltage characteristics under the different operating conditions of the NEDC (New European Driving Cycle), WLTC (World Light Vehicle Test Cycle) and CLTC (China Light Duty Vehicle Test Cycle). The influence of the output voltage of the power battery under different operating conditions is studied to ensure that the power battery can output energy with high efficiency. The operating conditions have an impact on the output voltage with an idle voltage fluctuation of the operating conditions. The nominal voltage variation and the number of series and parallel connections of the battery cells affect the frequency and time of breakdown. Full article

Background/Objectives: In this study, we aimed to analyze the changes in the expression profiles of selected messenger RNAs (mRNAs) and their encoded proteins in the tears of patients undergoing photorefractive keratectomy (PRK), femtosecond-assisted laser in situ keratomileusis (FS-LASIK), and small-incision lenticule extraction (SMILE) procedures. Methods: A total of 120 patients were divided into three groups based on the laser vision correction (LVC) procedure: PRK, FS-LASIK, or SMILE. Tear samples were collected preoperatively and at 1, 7, 30, and 180 days postoperatively. The expression levels of selected messenger RNAs (mRNAs) and proteins were analyzed by using reverse transcription quantitative polymerase chain reaction (RT-qPCR) and enzyme-linked immunosorbent assay (ELISA), respectively. Results: PRK and FS-LASIK elicited significantly stronger biological responses than SMILE. Interleukin-15 (IL-15) expression increased notably in the PRK and FS-LASIK groups, with mRNA levels reaching fold changes of 4.65 ± 0.65 and 4.99 ± 0.28, respectively, on day 1, compared with only 2.09 ± 0.23 in the SMILE group. Vascular endothelial growth factor A (VEGFA) levels were also elevated in the PRK (2.98 ± 0.23 fold change) and FS-LASIK groups (3.45 ± 1.09 fold change) on day 1, while the SMILE group showed minimal fluctuations. The protein concentration analysis based on the ELISA confirmed these trends, with IL-15 levels peaking at 54.2 ± 2.5 pg/mL in the PRK group and 52.8 ± 3.1 pg/mL in the FS-LASIK group, compared with 32.4 ± 1.9 pg/mL in the SMILE group on day 1. Similarly, VEGFA protein concentrations were the highest in the PRK (72.4 ± 4.1 pg/mL) and FS-LASIK patients (69.5 ± 3.8 pg/mL) on day 1 but remained low in the SMILE patients (45.6 ± 2.3 pg/mL). By day 180, gene expression and protein levels in all groups had stabilized, returning to near-preoperative values. Conclusions: PRK and FS-LASIK induced more pronounced molecular and protein-level changes during corneal wound healing than the less invasive SMILE procedure, indicating stronger biological responses. These findings suggest that tailored postoperative care based on the specific procedure could optimize healing and patient outcomes. However, further research with larger sample sizes and longer follow-ups is needed to confirm these observations and develop personalized treatment strategies. Full article

The growth of high-quality in vitro potato plants (Solanum stenotomum subsp. stenotomum, Solanum stenotomum subsp. goniocalyx, and Solanum tuberosum subsp. andigena) is affected by multiple biological, operational, and environmental factors. Research on in vitro culture is frequently focused on the species, explant, composition of the culture medium, and incubation conditions, but only limited information is available on the effect of the gas exchange rate and volume of in vitro culture vessels under variable planting densities. In the present study, these factors were evaluated with a set of seven diverse potato landraces. The results were compared to the plants’ responses in routinely used in vitro culture vessels, i.e., 13 × 100 mm and 25 × 150 mm test tubes, and GA7^® magenta vessels. In vitro potato plants grown in plastic vessels equipped with a HEPA filter delivering a high gas exchange rate developed thicker stems (0.95 mm), a higher total average leaf area (2.51 cm²), increased chlorophyll content in leaves (32.2 ppm), and lower moisture content in their tissues (90.1%) compared to filter systems with lower gas exchange rates. A high planting density of 10 × 10 plants per vessel (360 and 870 mL) negatively affected the average stem width and root length but increased the plant height (3.4 cm). High fluctuations of ion-uptake of NO₃⁻, Ca⁺⁺, K⁺, and Na⁺ were observed between genotypes, with some accessions having a 4.6-times higher Ca⁺⁺-ion concentration in their tissues (190–234 ppm). The in vitro plants developed more robust stems, longer roots, and larger leaves within in vitro culture vessels equipped with a HEPA filter (high gas exchange rate) compared to the control vessels, in contrast to the chlorophyll content in leaves, which was higher in plants grown in narrow test tubes. Depending on the purpose of the subculture of in vitro plants, their growth and development can be molded using different gas exchange rates, planting densities, and vessel volumes. Full article

This paper presents a novel approach to manage distributed DC microgrids (DCMG) by integrating a time-of-use (ToU) electricity pricing scheme and an internal price rate calculation mechanism. The proposed power-management system is designed to effectively handle uncertainties such as utility grid (UG) availability, fluctuating electricity prices, battery state of charge (SOC) levels, and frequent plug-ins and plug-outs of electric vehicles (EVs). Uncertainties in DCMG systems often lead to inefficiencies, power imbalances, and inexact voltage regulation issues within DCMGs. In addition, to maintain the power balance and constant voltage regulation under various operational states, the proposed scheme also incorporates secondary control into the DCMG power-management system. Unlike the existing approaches that often fail to adapt dynamically to changing conditions, the proposed method is the first approach to consider the concept of internal price rate in designing the DCMG power management. To address this challenge, this approach proposes a more resilient power-management strategy to enhance the efficiency and adaptability of DCMG systems. Extensive simulations and experimental validations demonstrate the practicality and adaptability of the proposed control strategy under diverse test conditions, including operation transitions between grid-connected mode (GCM) and islanded mode (IM), low battery SOC condition, operation transition from the current control mode (CCM) to distributed secondary control mode (DSCM), and EV plug-in scenarios. The test results confirm that the proposed method enhances the reliability, efficiency, and economic viability of DCMG systems, making it a promising solution for future smart grid and renewable energy integrations. Full article