DC line protection with high speed and strong robustness against high fault resistance is essential in highvoltage direct current(HVDC)*** conventional voltagederivative-based protections for DC lines exhibit the prob...
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DC line protection with high speed and strong robustness against high fault resistance is essential in highvoltage direct current(HVDC)*** conventional voltagederivative-based protections for DC lines exhibit the problem of low reliability on the occurrence of high-impedance *** this paper,fault traveling waves at the fault point and at the line side of the DC reactor are first analyzed using phasemodal *** on the theoretical analysis of the modal fault-component voltages at the line side of the DC reactor,a novel hybrid protection scheme utilizing the single-ended rate of change of voltage(ROCOV)and waveform similarity coefficient is *** utilizes the hybrid ROCOV criterion and waveform similarity coefficient to identify the faulted line and the amplitudes of the 0-and 1-mode fault-component voltages to identify fault type,and the polarities of the 0-and 1-mode fault-component voltages to identify faulted *** under various fault conditions verify that the proposed protection scheme can achieve fast and reliable identification of faulted line,fault type,and faulted pole in 1 ms,and effectively improve the reliability against high-impedance faults up to 1200.
The complexity of alarm detection and diagnosis tasks often results in a lack of alarm log *** to the strong rule associations inherent in alarm log data,existing data augmentation algorithms cannot obtain good result...
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The complexity of alarm detection and diagnosis tasks often results in a lack of alarm log *** to the strong rule associations inherent in alarm log data,existing data augmentation algorithms cannot obtain good results for alarm log *** address this problem,this paper introduces a new algorithm for augmenting alarm log data,termed APRGAN,which combines a generative adversarial network(GAN)with the Apriori *** generates alarm log data under the guidance of rules mined by the rule ***,we propose a new dynamic updating mechanism to alleviate the mode collapse problem of the *** addition to updating the real reference dataset used to train the discriminator in the GAN,we dynamically update the parameters and the rule set of the Apriori algorithm according to the data generated in each *** extensive experimentation on two public datasets,it is demonstrated that APRGAN surpasses other data augmentation algorithms in the domain with respect to alarm log data augmentation,as evidenced by its superior performance on metrics such as BLEU,ROUGE,and METEOR.
Roof-cutting blasting by explosives involves certain operational risks and is prone to cause damage to surrounding rock. Accordingly, a new non-explosive directional rock-breaking technology called Instantaneous Expan...
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Roof-cutting blasting by explosives involves certain operational risks and is prone to cause damage to surrounding rock. Accordingly, a new non-explosive directional rock-breaking technology called Instantaneous Expansion with a Single Fracture (IESF) has been developed. This paper focuses on the research of the crack propagation behavior and damage extent of rock mass under the action of IESF. Firstly, the directional rock-breaking principle of IESF is analyzed, and the theoretical radius of the crushed zone (R-c) and fracture zone (R-f) for conventional blasting (CB), shaped-charge blasting (SCB), and IESF under cylindrical charge conditions are derived. Subsequently, a field comparative experiment of the three methods was conducted. The results showed that CB produced cracks in random orientations around the hole wall, SCB produced secondary cracks in addition to two primary cracks in splitting direction, and the cracks produced by CB and SCB contain both Mode I and Mode II. Conversely, IESF only produces Mode I cracks in the presplitting direction. Finally, R-c and R-f of the three numerical models considering the rock mass heterogeneity were statistically analyzed, the results demonstrate that R-c (IESF) < R-c (SCB) < R-c (CB), while R-f (IESF) > R-f (SCB) > R-f (CB). The statistical analysis of the monitoring point pressure and Young's modulus during the damage process further verified the directional rock-breaking mechanism of IESF. The research results have improved the theoretical system of IESF and contributed to the promotion and application of IESF technology.
The increasing penetration of renewable energy resources with highly fluctuating outputs has placed increasing concern on the accuracy and timeliness of electric power system state estimation(SE).Meanwhile,we note tha...
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The increasing penetration of renewable energy resources with highly fluctuating outputs has placed increasing concern on the accuracy and timeliness of electric power system state estimation(SE).Meanwhile,we note that only a fraction of system states fluctuate at the millisecond level and require to be *** such,refreshing only those states with significant variation would enhance the computational efficiency of SE and make fast-continuous update of states ***,this is difficult to achieve with conventional SE methods,which generally refresh states of the entire system every 4–5 *** this context,we propose a local hybrid linear SE framework using stream processing,in which synchronized measurements received from phasor measurement units(PMUs),and trigger/timingmode measurements received from remote terminal units(RTUs)are used to update the associated local ***,the measurement update process efficiency and timeliness are enhanced by proposing a trigger measurement-based fast dynamic partitioning algorithm for determining the areas of the system with states requiring *** particular,non-iterative hybrid linear formulations with both RTUs and PMUs are employed to solve the local SE *** timeliness,accuracy,and computational efficiency of the proposed method are demonstrated by extensive simulations based on IEEE 118-,300-,and 2383-bus systems.
This work aims to investigate the mechanical properties and interfacial characteristics of 6061 Al alloy plates fabricated by hotroll bonding(HRB)based on friction stir *** results showed that ultimate tensile strengt...
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This work aims to investigate the mechanical properties and interfacial characteristics of 6061 Al alloy plates fabricated by hotroll bonding(HRB)based on friction stir *** results showed that ultimate tensile strength and total elongation of the hot-rolled and aged joints increased with the packaging vacuum,and the tensile specimens fractured at the matrix after exceeding 1 ***-equilibrium grain boundaries were formed at the hot-rolled interface,and a large amount of Mg_(2)Si particles were linearly precipitated along the interfacial grain boundaries(IGBs).During subsequent heat treatment,Mg_(2)Si particles dissolved back into the matrix,and Al_(2)O_(3) film remaining at the interface eventually evolved into *** addition,the local IGBs underwent staged elimination during HRB,which facilitated the interface healing due to the fusion of grains at the *** process was achieved by the dissociation,emission,and annihilation of dislocations on the IGBs.
Earthen ruins contain rich historical *** by wind speed,temperature,and other factors,their survival conditions are not *** series prediction provides more information for ruins *** work includes two challenges:(1)The...
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Earthen ruins contain rich historical *** by wind speed,temperature,and other factors,their survival conditions are not *** series prediction provides more information for ruins *** work includes two challenges:(1)The ruin is located in an open environment,causing complex nonlinear temporal ***,the usual wind speed monitoring requires the 10 meters observation height to reduce the influence of ***,in order to monitor wind speed around the ruin,we have to set 4.5 meters observation height according to the ruin,resulting in a non-periodic and oscillating temporal pattern of wind speed;(2)The ruin is located in the arid and uninhabited region of northwest china,which results in accelerating aging of equipment and difficulty in *** significantly amplifies the device error rate,leading to duplication,missing,and outliers in *** address these challenges,we designed a complete preprocessing and a Transformer-based multi-channel patch *** results on four datasets that we collected show that our model outperforms the *** climate prediction model can timely and effectively predict the abnormal state of the environment of the *** provides effective data support and decision-making for ruins conservation,and exploring the relationship between the environmental conditions and the living state of the earthen ruins.
Waveform diversity(WD) represents a dynamic and transformative technology widely used in radar systems to enhance sensitivity and discrimination capabilities. Recently, WD techniques have been extensively explored for...
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Waveform diversity(WD) represents a dynamic and transformative technology widely used in radar systems to enhance sensitivity and discrimination capabilities. Recently, WD techniques have been extensively explored for their potential ambiguity suppression within synthetic aperture radar(SAR) *** these, the alternate transmitting mode combined with orthogonal waveforms emerges as a particularly promising solution. This study focuses on optimizing the power spectrum density(PSD) of signals to design and generate an orthogonal waveform pair that achieves both a low cross-correlation-to-autocorrelation ratio(CAR) and satisfactory imaging performance. Initially, we construct a fractional programming model with convex constraints to minimize the CAR. To address this challenge, we introduce an iterative optimization procedure for the PSD variable, which sequentially reduces the CAR. Each optimization step can be efficiently solved using a quadratically constrained quadratic program, ensuring that the resulting computational complexity remains low. Building on the optimized PSD, we established a parametric piecewise linear model to generate an orthogonal waveform pair. This model not only maintains a low CAR but achieves satisfactory imaging performance in real-time applications. Consequently, this orthogonal waveform pair effectively suppresses range ambiguity in SAR systems. Finally, we demonstrated the practicability and effectiveness of the proposed orthogonal waveforms through detailed simulation experiments, specifically targeting ambiguity suppression in conventional quad-polarization SAR systems.
Extensive spatiotemporal analyses of long-trend surface ozone in the Yangtze River Delta(YRD)region and itsmeteorology-related and emission-related have not been systematically *** this study,by using 8-year-long(2015...
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Extensive spatiotemporal analyses of long-trend surface ozone in the Yangtze River Delta(YRD)region and itsmeteorology-related and emission-related have not been systematically *** this study,by using 8-year-long(2015–2022)surface ozone observation data,we attempted to reveal the variation ofmultiple timescale components using the Kolmogorov–Zurbenko filter,and the effects of meteorology and emissions were quantitatively isolated using multiple linear regression with meteorological *** results showed that the short-term,seasonal,and long-term components accounted for daily maximum 8-hr average O_(3)(O_(3–8)hr)concentration,46.4%,45.9%,and 1.0%,*** meteorological impacts account for an average of 71.8%of O_(3–8)hr,and the YRD’s eastern and northern sections aremeteorology-sensitive *** on statistical analysis technology with empirical orthogonal function,the contribution of meteorology,local emission,and transport in the long-term component of O_(3–8)hr were 0.21%,0.12%,and 0.6%,*** spatiotemporal analysis indicated that a distinct decreasing spatial pattern could be observed from coastal cities towards the northwest,influenced by the monsoon and synoptic *** central urban agglomeration north and south of the YRD was particularly susceptible to local *** the cities studied,Shanghai,Anqing,and Xuancheng,located at similar latitudes,were significantly impacted by atmospheric transmission—the contribution of Shanghai,the maximum accounting for 3.6%.
With the widespread use of lithium-ion batteries in electric vehicles,energy storage,and mobile terminals,there is an urgent need to develop cathode materials with specific ***,existing material control synthesis rout...
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With the widespread use of lithium-ion batteries in electric vehicles,energy storage,and mobile terminals,there is an urgent need to develop cathode materials with specific ***,existing material control synthesis routes based on repetitive experiments are often costly and inefficient,which is unsuitable for the broader application of novel *** development of machine learning and its combination with materials design offers a potential pathway for optimizing ***,we present a design synthesis paradigm for developing high energy Ni-rich cathodes with thermal/kinetic simulation and propose a coupled image-morphology machine learning *** paradigm can accurately predict the reaction conditions required for synthesizing cathode precursors with specific morphologies,helping to shorten the experimental duration and *** the model-guided design synthesis,cathode materials with different morphological characteristics can be obtained,and the best shows a high discharge capacity of 206 mAh g^(−1)at 0.1C and 83%capacity retention after 200 *** work provides guidance for designing cathode materials for lithium-ion batteries,which may point the way to a fast and cost-effective direction for controlling the morphology of all types of particles.
Copper, a widely used metal in industrial processes, generates copper-containing wastewater, leading to high-moisture sludge formation. Copper enrichment in the sludge reduces utilization and poses environmental risks...
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Copper, a widely used metal in industrial processes, generates copper-containing wastewater, leading to high-moisture sludge formation. Copper enrichment in the sludge reduces utilization and poses environmental risks. This study investigates the effects of various electromagnetic conditions (magnetic field intensity: 0-2.1 mT;voltage intensity: 0-15 V) on reducing sludge moisture and enhancing heavy metal copper removal during anaerobic composting. Additionally, the impact of CuCl2 solution addition in three anaerobic composting stages (low-temp LC, high-temp HC, medium-temp MC) on microbial communities is examined. Results show that with a 1.4 mT magnetic field and 10 V electric field, sludge moisture decreases significantly from 95 to 65%, and copper removal increases to 67%, yielding high-quality compost. Copper addition during composting also affects microbial activity, particularly in the LC stage. Copper promotes beneficial microorganisms like Proteobacteria and Firmicutes, enhancing organic substrate degradation. Furthermore, Cu2+ involvement regulates microbial metabolic reactions, aiding system stability through biological *** findings provide crucial theoretical and practical evidence for optimizing anaerobic composting, reducing sludge moisture, and enhancing heavy metal removal efficiency.
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