Search Results (60)

Vehicular ad hoc networks (VANETs) must simultaneously satisfy stringent reliability, latency, and sustainability targets under highly dynamic urban and highway mobility. Existing solutions typically optimise one or two dimensions (link stability, clustering, or energy) but lack an integrated, adaptive mechanism that fuses heterogeneous metrics while remaining lightweight and deployable. This paper introduces a VANET routing protocol named SYMPHONY (Synergistic Hierarchical Metric-Fusion and Predictive Hybrid Optimization for Network Yield) that operates in three coordinated layers: (i) a compact neighbourhood filtering stage that reduces forwarding scope and eliminates transient relays, (ii) a cluster layer that elects resilient cluster heads using fuzzy energy-aware metrics and backup leadership, and (iii) a global inter-cluster optimizer that blends a GA-reseeded swarm metaheuristic with a stability-aware pheromone scheme to produce multi-objective routes. Crucially, SYMPHONY employs an ultra-lightweight online weight-adaptation module (contextual linear bandit) to tune metric fusion weights in response to observed rewards (packet delivery ratio, end-to-end delay, and Green Performance Index). We evaluated the proposed routing protocol SYMPHONY versus strong modern baselines across urban and highway scenarios with varying density and resource constraints. The results demonstrate that SYMPHONY improves packet delivery ratio by up to 12–18%, reduces latency by 20–35%, and increases the Green Performance Index by 22–45% relative to the best baseline, while keeping control overhead and per-node computation within practical bounds. Full article

The coordinated development of stems and branches, together with optimal strip spacing, is crucial for improving soybean yield in the soybean–maize relay strip intercropping system. Shading during the seedling stage often causes excessive stem elongation and reduced branching; however, the physiological mechanisms underlying stem–branch responses to changing light environments remain unclear. This study aimed to clarify how early-stage shading and subsequent light recovery regulate stem and branch development through changes in canopy light environment, phytohormones, and the expression of related genes. Shade-tolerant Nandou12 and shade-sensitive Nannong99-6 were used as experimental soybean cultivars. Six treatments were implemented: a non-shaded control with uniform strip spacing (T0: 40 cm); seedling shading (40% PAR-transmission nets for 35 days after emergence) combined with variable strip spacing (T1: 40 cm; T2: 70 cm; T3: 100 cm; T4: 130 cm; T5: 160 cm). Canopy light environment, main stem and branch traits, photosynthetic characteristics, phytohormones, related gene expression, and yield components were measured. The results indicated that shade at the seedling stage significantly upregulated auxin (IAA) biosynthesis gene GmYUCC and downregulated phytochrome gene GmPhyB in the main stem tips, corresponding to increased IAA and cytokinins (CKs). In branch tips, shading significantly downregulated GmYUCC and GmPhyB while upregulated GmMAX3B, which is consistent with reduced levels of IAA, CKs, and brassinosteroid (BR), and increased strigolactones (SLs). After light recovery, GmPhyB and GmYUCC were upregulated whereas GmMAX3B was downregulated, accompanied by higher IAA, GA, CKs, and BRs, lower SLs, and improved chlorophyll content, Rubisco content, photosynthesis, and the accumulation of soluble sugar and starch in branches. Nandou12 achieved up to 10% higher yield under shading, and a 100 cm strip spacing maintained 74–111% yield of the non-shaded soybean. These findings demonstrate that cultivars with strong shade tolerance and high branching potential, combined with a 100-cm strip spacing, effectively sustain yield in relay-intercropped soybean by enabling favorable physiological responses to early shading and subsequent light recovery. Full article

In this study, the PM_2.5 pollution transport budget in the atmospheric boundary layer (ABL) of Beijing–Tianjin–Hebei (BTH) and Chengdu–Chongqing (CY) was quantitatively evaluated from the perspective of horizontal and vertical exchange. Based on the aircraft meteorological data relay (AMDAR) observation data, the study found that the vertical exchange process of pollutants is mainly influenced by the combined effects of meteorological conditions and topographical factors. Meteorological factors determine the direction and intensity of the vertical exchange, while the complexity of the terrain affects the exchange pattern through local circulation and air flow convergence. The characteristics of the pollution transport budget between the BTH and CY regions show that the BTH region has a net output of pollutants throughout the year, while the CY region has a net input of pollutants. The total transport budget of the four typical representative seasons in BTH is negative. It indicated that BTH, as the region with the highest intensity of air pollution emission in China, is dominated by outward transport of air pollutants to surrounding regions. Due to the influence of topographic and meteorological conditions in the CY region, the air pollutants tend to accumulate in the basin rather than diffuse. The transport budget relationship of the four seasons is positive and the input of air pollutants can be obviously simulated. Combined with the results of the vertical wind profile, Beijing is more vulnerable to the prevailing cold air sinking in the northwest in winter, which is characterized by the inflow of the free troposphere (FT) into the ABL. As for Chongqing, it is blocked by mountains so that the gas convection at the top of the ABL is obvious. This horizontal convergence phenomenon induces upward vertical movement, which makes Chongqing show a strong characteristic of the ABL transport to the FT. Full article

Underground mining environments are highly hazardous, often prone to gas explosions, cave-ins, and fires that may trap miners during emergencies. The accurate, real-time localization of miners is vital for effective self-escape and rescue operations. Although the Mine Improvement and New Emergency Response (MINER) Act of 2006 mandates communication and tracking systems, most current solutions rely on low-power devices and line-of-sight methods that are ineffective in GPS-denied, dynamic subsurface conditions. Delay-Tolerant Networking (DTN) has emerged as a promising alternative by supporting message relay through intermittent links. In this work, we propose a deep learning framework that combines Convolutional Neural Networks (CNNs) and Long Short-Term Memory (LSTM) networks to predict miner locations using simulated DTN-based movement data. The model was trained on a simulated dataset of 1,048,575 miner movement entries, predicting miner locations across 26 pillar classes. It achieved an 89% accuracy, an 89% recall, and an 83% F1-score, demonstrating strong performance for real-time underground miner localization. These results demonstrate the model’s potential for the real-time localization of trapped miners in GPS-denied environments, supporting enhanced self-escape and rescue operations. Future work will focus on validating the model with real-world data and deploying it for operational use in mines. Full article

As the key non-electric protection equipment of an oil-immersed transformer, the gas relay plays an important role in ensuring the safe operation of the transformer. To further enhance the sensitivity of gas relays for the heavy gas alarm, this paper takes the BF type double float gas relay as the research object and proposes a new method for heavy gas setting, which is based on the internal oil flow acceleration characteristics of the gas relay. Firstly, the analytical derivation of the force acting on the gas relay baffle is carried out, and through theoretical analysis, the internal mechanism of heavy gas action under transient oil flow excitation is revealed. Then, the numerical simulation and experimental research on the variation of oil flow velocity and acceleration under different fault energies are carried out. The results show that with the increase of fault energy, the oil flow velocity fluctuates up and down during heavy gas action, but the oil flow acceleration shows a linear correlation. The oil flow acceleration can be set as the threshold of heavy gas action, and the severity of the fault can be judged. At the same time, the alarm time of the heavy gas setting method based on the oil flow acceleration characteristics is greatly shortened, which can reflect the internal fault of the transformer in time and significantly improve the sensitivity of the heavy gas alarm. Full article

In the context of global climate governance and the low-carbon energy transition, virtual power plant (VPP), a key technology for integrating distributed energy resources, is urgently needed to solve the problem of decentralization and lack of synergy in electricity, carbon, and green certificate trading. Existing studies mostly focus on single energy or carbon trading scenarios and lack a multi-market coupling mechanism supported by blockchain technology, resulting in low transaction transparency and a high risk of information tampering. For this reason, this paper proposes a synergistic optimization strategy for electricity/carbon/green certificate virtual power plants based on blockchain cross-chain transactions. First, Latin Hypercubic Sampling (LHS) is used to generate new energy output and load scenarios, and the K-means clustering method with improved particle swarm optimization are combined to cut down the scenarios and improve the prediction accuracy; second, a relay chain cross-chain trading framework integrating quota system is constructed to realize organic synergy and credible data interaction among electricity, carbon, and green certificate markets; lastly, the multi-energy optimization model of the virtual power plant is designed to integrate carbon capture, Finally, a virtual power plant multi-energy optimization model is designed, integrating carbon capture, power-to-gas (P2G) and other technologies to balance the economy and low-carbon goals. The simulation results show that compared with the traditional model, the proposed strategy reduces the carbon emission intensity by 13.3% (1.43 tons/million CNY), increases the rate of new energy consumption to 98.75%, and partially offsets the cost through the carbon trading revenue, which verifies the Pareto improvement of environmental and economic benefits. This study provides theoretical support for the synergistic optimization of multi-energy markets and helps to build a low-carbon power system with a high proportion of renewable energy. Full article

Currently, the cement industry stands as one of the sectors with the most significant environmental impact, primarily due to its substantial greenhouse gas emissions and energy consumption. To mitigate this impact, a roadmap has been followed in recent years, outlining a set of objectives aimed at diminishing the environmental footprint of the construction industry. This research focuses on the development of mortars with different water/cement ratios employing an alternative cement, specifically magnesium phosphate cement (MPC) formulated with secondary sources. The goal of this research relays in developing mortars based on MPC by using waste from the metallurgical industry, named tundish deskulling waste (TUN), as an MgO source. The results revealed the optimal water/cement (W/C) ratio for MPC-TUN mortars production through the assessment of various characterization techniques, which was 0.55. This ratio resulted in the highest compressive strength after 28 days of curing and the formation of a stable K-struvite matrix. Furthermore, it demonstrated the effectiveness of aluminum sulphate in preventing efflorescence caused by carbonates. The development of alternative masonry mortars for application in building materials represents a significant stride towards advancing the principles of a circular economy, in alignment with the objectives laid out in the 2030 roadmap. Full article

With its unique environment and strategic value, the near space (NS) has become the focus of global scientific and technological, military, and commercial fields. Aiming at the problem of communication interruption when the aircraft re-enters the atmosphere, to ensure the needs of communication, navigation, and telemetry, tracking, and command (TT&C), this paper proposes an overall integration of communication, navigation, and TT&C (ICNT) signals scheme based on the K/Ka frequency band. Firstly, the K/Ka frequency band is selected according to the ITU frequency division, high-speed communication requirements, advantages of space-based over-the-horizon relay, overcoming the blackout problem, and the development trend of high frequencies. Secondly, the influence of the physical characteristics of the NS on ICNT is analyzed through simulation. The results show that when the K/Ka signal is transmitted in the NS, the path loss changes significantly with the elevation angle. The bottom layer loss at an elevation angle of 90° is between 143.5 and 150.5 dB, and the top layer loss is between 157.5 and 164.4 dB; the maximum attenuation of the bottom layer and the top layer at an elevation angle of 0° is close to 180 dB and 187 dB, respectively. In terms of rainfall attenuation, when a 30 GHz signal passes through a 100 km rain area under moderate rain conditions, the horizontal and vertical polarization losses reach 225 dB and 185 dB, respectively, and the rainfall attenuation increases with the increase in frequency. For gas absorption, the loss of water vapor is higher than that of oxygen molecules; when a 30 GHz signal is transmitted for 100 km, the loss of water vapor is 17 dB, while that of oxygen is 2 dB. The loss of clouds and fog is relatively small, less than 1 dB. Increasing the frequency and the antenna elevation angle can reduce the atmospheric scintillation. In addition, factors such as the plasma sheath and multipath also affect the signal propagation. In terms of modulation technology, the constant envelope signal shows an advantage in spectral efficiency; the new integrated signal obtained by integrating communication, navigation, and TT&C signals into a single K/Ka frequency point has excellent characteristics in the simulation of power spectral density (PSD) and autocorrelation function (ACF), verifying the feasibility of the scheme. The proposed ICNT scheme is expected to provide an innovative solution example for the communication, navigation, and TT&C requirements of NS vehicles during the re-entry phase. Full article

SF₆ gas has high electrical insulation strength and excellent arc-extinguishing properties, making it widely used in high-voltage equipment. However, gas leakage or liquefaction can reduce its performance, necessitating density monitoring. This paper presents an online calibration device based on balance pressure measurement and outlines the calibration process. It also analyzes the impact of factors such as the measuring balance, gravitational acceleration, cylinder friction, and installation alignment on calibration accuracy. To address uncertainty in the stabilization time of the cylinder gas temperature, a simulation model was created to observe the temperature equilibrium. Furthermore, power consumption analysis of the test device was conducted under different calibration cycles. The experimental results confirm the effectiveness of this calibration strategy. Full article

In practical engineering, due to the residual magnetism in the iron core of the converter transformer, the inrush current is generated in the case of no-load closing, and the inrush current leads to an oil flow surge inside the converter transformer. Under the influence of oil flow, the gas relay plate will be deflected, and when the deflection angle is too large, the gas relay will malfunction. Because of the lacking research on the influence of the misoperation of the gas relay under the excitation inrush of the converter transformer, it is difficult to effectively suppress the misoperation of gas relay under inrush current. Therefore, the finite element model of the electromagnetic hydraulic coupling of the converter transformer is established in this paper to obtain the oil flow velocity through the gas relay under the inrush current. A fluid–solid coupling model was established inside the gas relay to study the deflection characteristics of the baffle of the gas relay under the inrush current, and the relationship between the inrush current amplitude and the deflection angle of the baffle was mathematically fitted to effectively predict whether the gas relay has the risk of misoperation. From the experimental results, it can be seen that when the amplitude of the inrush current exceeds 6.37 kA, the gas relay will have the risk of misoperation. Finally, the influence of oil flow impact on the gas relay baffle under multiple cycles is considered. The results can provide an effective reference for analyzing the diagnosis of gas relay misoperation under the effect of inrush current. Full article

The gas relay is a common non-electric protection device inside transformers, installed on the connecting pipeline between the transformer oil tank and the oil conservator. When the transformer malfunctions and the oil flow value reaches the heavy gas setting value of the gas relay, a heavy gas alarm is triggered. Therefore, accurately analyzing the heavy gas action characteristics and the setting value of the gas relay directly affects the accuracy of the heavy gas alarm. The BF(Bi-Float) type double float ball gas relay uses steady-state oil flow to calibrate the setting values of heavy gas action. In reality, transformer faults cause transient oil flow. To explore the relationship between the oil flow state and gas relay flow velocity setting values, a dynamic model of the heavy gas action process of BF type double float ball gas relay was first established, and the influence of the oil flow state on the gas relay baffle action process was analyzed. Then, a transient oil flow impact test bench was developed to experimentally study the heavy gas action characteristics of gas relays under different intensities of transient oil flow impact. Theoretical and experimental research results indicate that different oil flow impact states have a significant effect on the flow velocity setting values of gas relays. The flow velocity setting value of the BF type double float ball gas relay used in this study under transient oil flow impact is 0.8 m/s, which is lower than its factory flow velocity setting value of 1 m/s. These research results have positive significance for optimizing the performance of gas relays and improving the operational reliability of power transformers. Full article

Trip faults are obviously increased by frequent lightning strikes, and increasing lightning trip-out seriously affects a system’s stability and power supply reliability. In this paper, the reasons for high lightning trip-out rates in electric power transmission lines are analyzed in detail from three perspectives, as follows: the substandard lightning resistance level, lightning complexity at a mid-point between towers, and the complexity of first and subsequent lightning stroke conditions. Experiments and simulations demonstrate that the solid-phase gas arc-extinguishing method has a strong ability to extinguish power–frequency continuous-current arcs and to protect against first and subsequent lightning strokes. Since the time taken by gas arc-extinguishing is much less than the response time of relay protection, trip accidents caused by lightning strikes can be avoided and the trip rates of lightning strikes can be reduced using this method. The case analysis and practical operation results show that the solid-phase gas arc-extinguishing lightning protection method can reduce the lightning trip-out rate by more than 90%, completely solve the problem of high lightning trip-out rates, and significantly improve the reliability of power supply. Full article

The production of organic meat and dairy products relies on limited organic protein meal supplies. Camelina (Camelina sativa L.) may sustainably increase organic protein meal supplies. Using grain production trial data, research literature, and camelina feeding trial results, greenhouse gas (GHG) emissions and fossil energy impacts were modeled for inclusion of 10% camelina meal in swine finishing diets using life cycle analysis (LCA). Two key grain production scenarios were examined: field trial relay (FTR) camelina and a higher yielding as expected relay (AER) camelina, with a baseline monocrop soybean (MCS). At the grain production stage, the FTR, AER, and MCS scenarios emitted 0.65, 0.43, and 0.13 kg of CO₂ eq./kg DM grain harvested, respectively. At the meal production stage, 0.61, 0.40, and 0.15 kg of CO₂ eq. were emitted per kg of protein meal from the FTR, AER, and MCS scenarios, respectively. GHG emissions from the finishing phase of pork production were 1.43, 1.38, and 1.31 kg CO₂ eq./kg live weight pigs produced for the FTR, AER, and MCS scenarios, respectively. Findings were similar for fossil energy use. The higher environmental burdens from camelina grain production due to reduced yields of both camelina and soybean resulted in negative environmental performance in camelina-amended diets. Full article

Protecting AC microgrids (MGs) is a challenging task due to their dual operating modes—grid-connected and islanded—which cause sudden variations in fault currents. Traditional protection methods may no longer ensure network security. This paper presents a novel approach to protection coordination in AC MGs using non-standard features of directional over-current relays (DOCRs). Three key optimization variables are considered: Time Multiplier Setting (TMS), the plug setting multiplier’s (PSM) maximum limit, and the standard characteristic curve (SCC). The proposed model is formulated as a mixed-integer nonlinear programming problem and solved using four metaheuristic techniques: the genetic algorithm (GA), Imperialist Competitive Algorithm (ICA), Harmonic Search (HS), and Firefly Algorithm (FA). Tests on a benchmark IEC MG with distributed generation and various operating modes demonstrate that this approach reduces coordination times compared to existing methods. This paper’s main contributions are threefold: (1) introducing a methodology for assessing the optimal performance of different standard curves in MG protection; (2) utilizing non-standard characteristics for optimal coordination of DOCRs; and (3) enabling the selection of curves from both North American and European standards. This approach improves trip time performance across multiple operating modes and topologies, enhancing the reliability and efficiency of MG protection systems. Full article

In order to reduce the frequency of high-frequency Doppler signal light, the electronic bandwidth of a data acquisition system is reduced. This paper mainly describes the principle and experimental verification results of optical multistage cascade frequency reduction technology. The bandwidth requirement of the detector and the oscilloscope is reduced by the method of “relaying” the measured beat frequency signal between multiple electronic channels. Aiming to achieve the requirement of ultra-high speed measurement of 22 km/s, the requirement of the original signal frequency as high as 28 GHz electrical bandwidth is reduced to the acquisition and recording system with only 8 GHz bandwidth. A complete velocity profile of up to 11.47 km/s is measured on a three-stage light gas gun with velocity measurement accuracy of 1%. Full article