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An adaptive finite-difference method for seismic traveltime modeling based on 3D eikonal equation

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Petroleum Science 2024年第1期21卷 195-205页

作者： Bao-ping Qiao Qing-Qing Li Wei-guang he Dan Zhao Qu-Bo Wu CNNC Beijing Research Institute of Uranium Geology Beijing 100029China National Key Laboratory of Deep Oil and Gas China University of Petroleum(East China)Qingdao 266580ShangdongChina SINOPEC Geophysical Research Institute Nanjing211103JiangsuChina

3D eikonal equation is a partial differential equation for the calculation of first-arrival traveltimes and has been widely applied in many scopes such as ray tracing,source localization,reflection migration,seismic monitoring and tomographic *** recent years,many advanced methods have been developed to solve the 3D eikonal equation in heterogeneous ***,there are still challenges for the stable and accurate calculation of first-arrival traveltimes in 3D strongly inhomogeneous *** this paper,we propose an adaptive finite-difference(AFD)method to numerically solve the 3D eikonal *** novel method makes full use of the advantages of different local operators characterizing different seismic wave types to calculate factors and traveltimes,and then the most accurate factor and traveltime are adaptively selected for the convergent updating based on the Fermat *** with global fast sweeping describing seismic waves propagating along eight directions in 3D media,our novel method can achieve the robust calculation of first-arrival traveltimes with high precision at grid points either near source point or far away from source point even in a velocity model with large and sharp *** numerical examples show the good performance of the AFD method,which will be beneficial to many scientific applications.

关键词： 3D eikonal equation Accurate traveltimes Global fast sweeping 3D inhomogeneous media Adaptive finite-difference method

Persistent Currents and Edge States in a Quasi-One-Dimensional Mesoscopic Ring with a Screened Interaction

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Communications in Theoretical Physics 2002年第5期38卷 621-628页

作者： he guang-ping LI Hua-Zhong Advanced Research Center Zhongshan University Guangzhou 510275 China Advanced Research Center Zhongshan University Guangzhou 510275 China

The effect ofthe edge state on the persistent current in quasi-1D mesoscopic rings with a screened interactionwhich exists only between nearest-neighboring particles is studied with the Hartree-Fock approximation. The theoreticalvalue of the current magnitude is greatly enhanced by both the edge state and the Coulomb interaction, and pinningthe electrons into a lattice is good for the enhancement if screening happens. In high dimensional systems the screeningeffect can make the interacting range show anisotropy, and create a tendency of gathering for particles with a repulsivepotential.

关键词： strongly correlated electron systems, persistent currents, edge states

Reaction mechanism between Al_(2)O_(3)–MgO refractory materials and rare earth high-carbon heavy rail steel

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Journal of Iron and Steel Research(International) 2024年第5期31卷 1153-1163页

作者： Yi Wang guang-jie Song ping Shen Jian-zhong he Da-xian Zhang Jian-xun Fu Center for Advanced Solidification Technology(CAST) School of Materials Science and EngineeringState Key Laboratory of Advanced Special SteelShanghai UniversityShanghai200444China State Key Laboratory of Baiyunebo Rare Earth Resources Research and Comprehensive Utilization Baotou014030Inner MongoliaChina Inner Mongolia Baotou Steel Union Co. Ltd.Baotou014030Inner MongoliaChina

Submerged entry nozzle(SEN)clogging is a major problem affecting the production quality of rare earth steel,and finding a suitable refractory outlet can significantly reduce production *** explore the relationship between refractory composition and interface interaction,unprotected coated Al_(2)O_(3)–MgO refractories and SiO2-coated Al_(2)O_(3)–MgO refractories were added to rare earth high-carbon heavy rail steel under laboratory conditions,and the Al_(2)O_(3)–MgO refractory was found to be more *** results show that,from the epoxy resin side to the refractory side,the contour of the refractory interface reaction layer can be divided into two main layers:an iron-rich reaction layer and an iron-poor reaction *** based on the spherical model suggest that the adhesion force is proportional to the size of the refractory particles and inclusions,and the same result applies to the surface *** the inclusions at a smaller size has a specific effect on alleviating the erosion of *** with the erosion mechanism of Al_(2)O_(3)–MgO refractories,the interface reaction mechanism between Al_(2)O_(3)–MgO refractories and molten steel was proposed,which provides ideas for solving SEN clogging.

关键词： Rare earth high-carbon heavy rail steel Al_(2)O_(3)-MgO refractory Adhesion Surface tension Interface interaction

Prediction of liquid circulation flow rate in RH degasser:improvement of decarburization at low atmospheric pressure

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Journal of Iron and Steel Research(International) 2024年第7期31卷 1661-1667页

作者： Gu-jun Chen Sheng-ping he College of Materials Science and Engineering Yangtze Normal UniversityChongqing 400044China College of Materials Science and Engineering Chongqing UniversityChongqing 400044China

The two-fluid model coupled with population balance model was used for simulating the gas-liquid flow in the Ruhrstahl-heraeus(RH)*** predicted circulation flow rate was compared with that measured from a water model experiment to validate the mathematical ***,influence of snorkel immersion depth on liquid circulation flow rate was numerically investigated under an atmospheric pressure of 101 and 84 kPa,*** result indicates that the circulation flow rate of the RH degasser in the high-altitude area was severely reduced because of the decrease in atmospheric ***,increasing the snorkel immersion depth from 0.5 to 0.7 m can compensate for the decrease in atmospheric *** test result indicates that decarburization rate is significantly enhanced by increasing the snorkel immersion *** optimization,the percentage of heats with a final carbon content less than 0.002 wt.%is significantly increased from 22.0%to 96.4%.

关键词： RH degasser Two-fluid model Population balance model-Circulation flow rate Decarburization Snorkel immersion depth

Volume of fluid simulation of single argon bubble dynamics in liquid steel under RH vacuum conditions

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Journal of Iron and Steel Research(International) 2024年第4期31卷 828-837页

Single argon bubble dynamics in liquid steel under Ruhrstahl-heraeus(RH)vacuum conditions were simulated using the volume of fluid method,and the ideal gas law was used to consider bubble growth due to heat transfer and pressure *** simulation with a constant bubble density was also performed to validate the numerical method,and the predicted terminal bubble shape and velocity were found to agree with those presented in the Grace diagram and calculated by drag correlation,*** simulation results under RH conditions indicate that the terminal bubble shape and velocity cannot be *** primary bubble growth occurs within a rising distance of 0.3 m owing to heating by the high-temperature liquid steel;subsequently,the bubble continues to grow under equilibrium with the hydrostatic *** the initial diameter is 8-32 mm,the bubble diameter and rising velocity near the liquid surface are 80-200 mm and 0.5-0.8 m/s,*** bubble rises rectilinearly with an axisymmetric shape,and the shape evolution history includes an initial sphere,(dimpled)ellipsoid,and spherical cap with satellite bubbles.

关键词： Bubble dynamics Liquid steel Volume of fluid Bubble growth Bubble shape Rising velocity

Channel assignment and power allocation for throughput improvement with PPO in B5G heterogeneous edge networks

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Digital Communications and Networks 2024年第1期10卷 109-116页

作者： Xiaoming he Yingchi Mao Yinqiu Liu ping ping Yan Hong Han Hu The College of Computer and Information Hohai UniversityNanjingChina The Key Laboratory of Water Big Data Technology of Ministry of Water Resources Hohai UniversityNanjing China The School of Computer Science and Engineering Nanyang Technological UniversitySingapore The College of Textile and Clothing Engineering Soochow UniversitySuzhouChina The College of Internet of Things Nanjing University of Posts and TelecomurunicationsNanjingChina

In Beyond the Fifth Generation(B5G)heterogeneous edge networks,numerous users are multiplexed on a channel or served on the same frequency resource block,in which case the transmitter applies coding and the receiver uses interference ***,uncoordinated radio resource allocation can reduce system throughput and lead to user inequity,for this reason,in this paper,channel allocation and power allocation problems are formulated to maximize the system sum rate and minimum user achievable *** the construction model is non-convex and the response variables are high-dimensional,a distributed Deep Reinforcement Learning(DRL)framework called distributed Proximal Policy Optimization(PPO)is proposed to allocate or assign ***,several simulated agents are trained in a heterogeneous environment to find robust behaviors that perform well in channel assignment and power ***,agents in the collection stage slow down,which hinders the learning of other ***,a preemption strategy is further proposed in this paper to optimize the distributed PPO,form DP-PPO and successfully mitigate the straggler *** experimental results show that our mechanism named DP-PPO improves the performance over other DRL methods.

关键词： B5G heterogeneous edge networks PPO Channel assignment Power allocation Throughput

P2P Energy Trading Considering Prosumer Preference and System Risk

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CSEE Journal of Power and Energy Systems 2024年第3期10卷 1179-1194页

作者： Xinyu he ping Dong Mingbo Liu Xuewei Huang Wenli Deng Ruijin he School of Electric Power Engineering South China University of TechnologyGuangzhou 510640China IEEE

As an important means of mobilizing demand-side resources,peer-to-peer(P2P)energy trading has drawn more and more attention from *** paper constructs a P2P energy trading framework considering prosumers’trading partner preferences(TPPs)and system *** first,we build the P2P trading models of prosumers equipped with different distributed energy resources(DERs),and TPP ***,to solve the established energy trading problem,a fully distributed double-consensus alternating direction method of multipliers(DC-ADMM)is proposed,which can achieve transaction consensus when considering market players’***,a risk-based security constrained economic dispatch(RBSCED)model based on AC power flow is established for the first time,by which a distribution system operator(DSO)checks system security and obtains risk-based locational marginal prices(RLMPs).Moreover,double-regulated price signals related to RLMPs which contain grid utilization prices(GUPs)and DSO’s retail prices realize management of players’*** the end,the proposed method is applied to an IEEE33 bus distribution *** show the proposed method effectively reduces system risk and ensures secure operation of system without direct management.

关键词： Double-consensus ADMM grid utilization price price signal risk-based locational marginal price trading partner preference

Towards understanding bogus traffic service in online social networks

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Frontiers of Information Technology & Electronic Engineering 2024年第3期25卷 415-431页

作者： ping he Xuhong ZHANG Changting LIN Ting WANG Shouling JI College of Computer Science and Technology Zhejiang UniversityHangzhou 310027China Binjiang Institute of Zhejiang University Hangzhou 310027China College of Information Sciences and Technology Pennsylvania State UniversityUniversity Park 17057-4846USA

Critical functionality and huge infuence of the hot trend/topic page(HTP)in microblogging sites have driven the creation of a new kind of underground service called the bogus traffic service(BTS).BTS provides a kind of illegal service which hijacks the HTP by pushing the controlled topics into it for malicious customers with the goal of guiding public *** hijack HTP,the agents of BTS maintain an army of black-market accounts called bogus trafic accounts(BTAs)and control BTAs to generate a burst of fake trafic by massively retweeting the tweets containing the customer desired topic(hashtag).Although this service has been extensively exploited by malicious customers,little has been done to understand *** this paper,we conduct a systematic measurement study of the *** first investigate and collect 125 BTS agents from a variety of sources and set up a honey pot account to capture BTAs from these *** then build a BTA detector that detects 162218 BTAs from Weibo,the largest Chinese microblogging site,with a precision of 94.5%.We further use them as a bridge to uncover 296916 topics that might be involved in bogus ***,we uncover the operating mechanism from the perspectives of the attack cycle and the attack *** highlights of our findings include the temporal attack patterns and intelligent evasion tactics of the *** findings bring BTS into the *** work will help in understanding and ultimately eliminating this threat.

关键词： Online social networks Measurement Bogus traffic Black market

Improving Federated Learning through Abnormal Client Detection and Incentive

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Computer Modeling in Engineering & Sciences 2024年第4期139卷 383-403页

作者： Hongle Guo Yingchi Mao Xiaoming he Benteng Zhang Tianfu Pang ping ping College of Computer and Information Hohai UniversityNanjing211100China Key Laboratory ofWater Big Data Technology of Ministry ofWater Resources Hohai UniversityNanjing211100China

Data sharing and privacy protection are made possible by federated learning,which allows for continuous model parameter sharing between several clients and a central *** reliable and high-quality clients must participate in practical applications for the federated learning global model to be accurate,but because the clients are independent,the central server cannot fully control their *** central server has no way of knowing the correctness of the model parameters provided by each client in this round,so clients may purposefully or unwittingly submit anomalous data,leading to abnormal behavior,such as becoming malicious attackers or defective *** reduce their negative consequences,it is crucial to quickly detect these abnormalities and incentivize *** this paper,we propose a Federated Learning framework for Detecting and Incentivizing Abnormal Clients(FL-DIAC)to accomplish efficient and security federated *** build a detector that introduces an auto-encoder for anomaly detection and use it to perform anomaly identification and prevent the involvement of abnormal clients,in particular for the anomaly client detection *** them,before the model parameters are input to the detector,we propose a Fourier transform-based anomaly data detectionmethod for dimensionality reduction in order to reduce the computational ***,we create a credit scorebased incentive structure to encourage clients to participate in training in order tomake clients actively *** training models(CNN,MLP,and ResNet-18)and three datasets(MNIST,Fashion MNIST,and CIFAR-10)have been used in *** to theoretical analysis and experimental findings,the FL-DIAC is superior to other federated learning schemes of the same type in terms of effectiveness.

关键词： Federated learning abnormal clients incentive credit score abnormal score detection