DC short-circuit faults pose a hazard to the operation of a modular multilevel converter(MMC)-based high voltage direct current(HVDC)system,necessitating reliable fault clearing solutions with rapid ***,because the pa...
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DC short-circuit faults pose a hazard to the operation of a modular multilevel converter(MMC)-based high voltage direct current(HVDC)system,necessitating reliable fault clearing solutions with rapid ***,because the parasitic capacitances of the main equipment oscillate with the lumped inductances of the HVDC system,strong electromagnetic oscillations with multiple frequencies occur during clearance *** oscillations will disturb the HVDC system’s protection and control ***,this paper focuses on the modeling of these ***,an equivalent circuit for the MMC-based HVDC system is proposed,taking into account the parasitic capacitances of the system’s major components,such as DC reactors,connecting cables,and DC circuit breakers(DCCBs).Second,four distinct oscillation stages are postulated based on action coordination of MMCs and DCCBs,and the associated analytical equations for the oscillation frequencies are ***,a 200 kV MMC-based DC converter station is subjected to an 6ms/6kA pole-to-pole(PTP)short-circuit *** oscillations have a frequency range of several kHz to several hundreds of *** measured waveforms correspond well with simulated results,including the parasitic ***,the relative errors between the simulated and measured frequencies are less than 5%.
A time-delay-dependent wide-area damping controller synthesis approach,based on Jensen’s integral inequality and evolution algorithm,is developed to suppress the adverse effect of time delay on the supplemental contr...
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A time-delay-dependent wide-area damping controller synthesis approach,based on Jensen’s integral inequality and evolution algorithm,is developed to suppress the adverse effect of time delay on the supplemental control of high-voltage direct current(DC)transmission ***,the state-space model of hybrid AC/DC systems with time delay is derived and the delay-dependent criteria for the stability of the closed-loop system are provided based on Jensen’s integral ***,initial solutions are randomly generated to overcome the difficulty of solving the nonlinear matrix ***,the time-delay stability upper bound of the controller is optimized using the differential evolution *** comparison to popular time-delay stable controller design methods,such as the free-weighting-matrix approach,the proposed method based on output feedback realization requires fewer decision variables and is more suitable for large-scale hybrid AC/DC *** examples are introduced to verify the effectiveness of the proposed method.
Vessel emissions have contributed a great deal to air quality deterioration in ***,the Chinese government has promulgated a series of stringent emission *** is in this context that vessel emission control technology r...
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Vessel emissions have contributed a great deal to air quality deterioration in ***,the Chinese government has promulgated a series of stringent emission *** is in this context that vessel emission control technology research is in full *** particular,during the 13th Five-Year Plan,the air pollution control technology of vessels has greatly *** emission control has followed two main governance routes:source emission reduction and aftertreatment *** control focuses on alternative fuels,with two main directions,the development of new fuels and the modification of existing ***,after-treatment technologies have also been developed,including wet desulfurization technology using seawater or alkaline liquids as wet washing liquids and selective catalytic reduction(SCR)for the control of NOx *** to china’s increasingly stringent emissions standards and regulations,work on the development of clean alternative fuels and further upgrading the collaborative application of after-treatment technologies to meet the near-zero-emissions requirements of vessels is still necessary.
The rapid spread of viral zoonoses can cause severe consequences,including huge economic loss,public health problems or even global crisis of *** detection technology plays a very important role in the prevention and ...
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The rapid spread of viral zoonoses can cause severe consequences,including huge economic loss,public health problems or even global crisis of *** detection technology plays a very important role in the prevention and control of such *** rapid and accurate detection of the pathogens of the diseases can directly lead to the early report and early successful control of the *** the advantages of being easy to use,fast,portable,multiplexing and cost-effective,semiconductor biosensors are kinds of detection devices that play an important role in preventing epidemics,and thus have become one of the research ***,we summarized the advances of semiconductor biosensors in viral zoonoses *** discussing the major principles and applications of each method for different pathogens,this review proposed the directions of designing semiconductor biosensors for clinical application and put forward perspectives in diagnostic of viral zoonoses.
With the help of advanced information technology,real-time monitoring and control levels of cyber-physical distribution systems(CPDS)have been significantly *** due to the deep integration of cyber and physical system...
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With the help of advanced information technology,real-time monitoring and control levels of cyber-physical distribution systems(CPDS)have been significantly *** due to the deep integration of cyber and physical systems,attackers could still threaten the stable operation of CPDS by launching cyber-attacks,such as denial-of-service(DoS)***,it is necessary to study the CPDS risk assessment and defense resource allocation methods under DoS *** paper analyzes the impact of DoS attacks on the physical system based on the CPDS fault self-healing ***,considering attacker and defender strategies and attack damage,a CPDS risk assessment framework is ***,risk assessment and defense resource allocation methods,based on the Stackelberg dynamic game model,are proposed under conditions in which the cyber and physical systems are launched ***,a simulation based on an actual CPDS is performed,and the calculation results verify the effectiveness of the algorithm.
Short video applications like Tik Tok have seen significant growth in recent *** common behavior of users on these platforms is watching and swiping through videos,which can lead to a significant waste of *** such,an ...
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Short video applications like Tik Tok have seen significant growth in recent *** common behavior of users on these platforms is watching and swiping through videos,which can lead to a significant waste of *** such,an important challenge in short video streaming is to design a preloading algorithm that can effectively decide which videos to download,at what bitrate,and when to pause the download in order to reduce bandwidth waste while improving the Quality of Experience(QoE).However,designing such an algorithm is non-trivial,especially when considering the conflicting objectives of minimizing bandwidth waste and maximizing *** this paper,we propose an end-to-end Deep reinforcement learning framework with Action Masking called DAM that leverages domain knowledge to learn an optimal policy for short video *** achieve this,we introduce a reward shaping technique to minimize bandwidth waste and use action masking to make actions more reasonable,reduce playback rebuffering,and accelerate the training *** have conducted extensive experiments using real-world video datasets and network traces including 4G/Wi Fi/*** results show that DAM improves the Qo E score by 3.73%-11.28%compared to state-of-the-art algorithms,and achieves an average bandwidth waste of only 10.27%-12.07%,outperforming all baseline methods.
In this paper,a theoretical framework of Multiagent Simulation(MAS)is proposed for strategic bidding in electricity markets using reinforcement learning,which consists of two parts:one is a MAS system used to simulate...
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In this paper,a theoretical framework of Multiagent Simulation(MAS)is proposed for strategic bidding in electricity markets using reinforcement learning,which consists of two parts:one is a MAS system used to simulate the competitive bidding of the actual electricity market;the other is an adaptive learning strategy bidding system used to provide agents with more intelligent bidding *** ExperienceWeighted Attraction(EWA)reinforcement learning algorithm(RLA)is applied to the MAS model and a new MAS method is presented for strategic bidding in electricity markets using a new Improved EWA(IEWA).From both qualitative and quantitative perspectives,it is compared with three other MAS methods using the Roth-Erev(RE),Q-learning and *** results show that the performance of the MAS method using IEWA is proved to be better than the *** four MAS models using four RLAs are built for strategic bidding in electricity *** running the four MAS models,the rationality and correctness of the four MAS methods are verified for strategic bidding in electricity markets using reinforcement learning.
Raman spectroscopy has found extensive use in monitoring and controlling cell culture *** this context,the prediction accuracy of Raman-based models is of paramount ***,models established with data from manually fed-b...
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Raman spectroscopy has found extensive use in monitoring and controlling cell culture *** this context,the prediction accuracy of Raman-based models is of paramount ***,models established with data from manually fed-batch cultures often exhibit poor performance in Raman-controlled ***,there is a need for effective methods to rectify these *** objective of this paper is to investigate the efficacy of Kalman filter(KF)algorithm in correcting Raman-based models during cell ***,partial least squares(PLS)models for different components were constructed using data from manually fed-batch cultures,and the predictive performance of these models was ***,various correction methods including the PLS-KF-KF method proposed in this study were employed to refine the PLS ***,a case study involving the auto-control of glucose concentration demonstrated the application of optimal model correction *** results indicated that the original PLS models exhibited differential performance between manually fed-batch cultures and Raman-controlled *** glucose,the root mean square error of prediction(RMSEP)of manually fed-batch culture and Raman-controlled culture was 0.23 and 0.40 g·L^(-1).With the implementation of model correction methods,there was a significant improvement in model performance within Raman-controlled *** RMSEP for glucose from updating-PLS,KF-PLS,and PLS-KF-KF was 0.38,0.36 and 0.17 g·L^(-1),***,the proposed PLS-KF-KF model correction method was found to be more effective and stable,playing a vital role in the automated nutrient feeding of cell cultures.
Calcium fluoride(CaF_(2))is an ideal adsorbent for the dehydration of gaseous hydrogen fluoride(HF)containing water *** this work,a novel CaF_(2)absorbent,spherical CaF_(2)nanoaggregates(NAs)with a closely packed stru...
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Calcium fluoride(CaF_(2))is an ideal adsorbent for the dehydration of gaseous hydrogen fluoride(HF)containing water *** this work,a novel CaF_(2)absorbent,spherical CaF_(2)nanoaggregates(NAs)with a closely packed structure,was proposed and efficiently fabricated by spray drying *** the building blocks of CaF_(2)NAs,the CaF_(2)nanoparticles(NPs)were prepared by the addition of excess calcium ions(Ca^(2+))or fluorine ions(F−)in the *** results indicated that the CaF_(2)NPs synthesized by excess Ca^(2+)and the corresponding NAs exhibited much better water vapor adsorption properties than their counterparts by excess F−,owing to higher zeta *** importantly,whether excess Ca^(2+)or F^(−),CaF_(2)NAs had further enhanced water vapor adsorption capacity compared to primary CaF_(2)NPs,possibly owing to their unique nano-micro secondary structures and higher surface *** work has great potential in the development of high-performance absorbents for separating moisture from corrosive gas HF.
Aluminum alloy is widely applied to the aerospace ***,the inspection of thin plates using Time-of-Flight Diffraction(TOFD)technique is restricted by the near-surface dead zone because of the coupling between diffracte...
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Aluminum alloy is widely applied to the aerospace ***,the inspection of thin plates using Time-of-Flight Diffraction(TOFD)technique is restricted by the near-surface dead zone because of the coupling between diffracted longitudinal wave and lateral *** halfskip mode-converted wave is introduced to decrease dead zone and detect defects in aluminum alloy thin plates by increasing ray path and propagation *** quantitative correlation for the diffracted shear wave from longitudinal back-wall wave is deduced in combination with the acoustic path,realizing the accurate location of shallow subsurface *** and experimental results indicate that the dead zone is decreased by 38% by the half-skip mode-converted wave,and the location errors are within 5% for the aluminum alloy plate with a thickness of 7.0 *** to other alternative TOFD techniques,half-skip mode-converted wave has better response amplitude and positioning accuracy,demonstrating strong applicability in TOFD inspection of thin plates.
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