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Journal of Computational Mathematics 2024年第2期42卷 415-431页

作者： Yanmi wu Dongyang Shi PLA Information Engineering University Zhengzhou 450001China School of Mathematics and Information Sciences Yantai UniversityYantai 264005China

In this paper,a two-grid mixed finite element method(MFEM)of implicit Backward Euler(BE)formula is presented for the fourth order time-dependent singularly perturbed Bi-wave problem for d-wave superconductors by the nonconforming EQ_(1)^(rot) *** this approach,the original nonlinear system is solved on the coarse mesh through the Newton iteration method,and then the linear system is computed on the fine mesh with Taylor’s *** on the high accuracy results of the chosen element,the uniform superclose and superconvergent estimates in the broken H^(1)-norm are derived,which are independent of the negative powers of the perturbation parameter appeared in the considered *** results illustrate that the computing cost of the proposed two-grid method is much less than that of the conventional Galerkin MFEM without loss of accuracy.

关键词： Time-dependent Bi-wave problem Two-grid mixed finite element method Uniform superclose and superconvergent estimates

Numerical simulation of fluid-thermal-structural coupling characteristics of stratospheric non-rigid airship

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CHINESE JOURNAL OF AERONAUTICS 2024年第9期37卷 224-236页

作者： Du, Huafei Lyu, Mingyun Yu, Chuan wu, Yifei wu, Yongmei Sun, Kangwen Beihang Univ Sch Aeronaut Sci & Engn Beijing 100191 Peoples R China Linzhou Ningbo Technol Co Ltd Yuyao 315042 Peoples R China

The voluminous stratospheric non-rigid airship is very sensitive to the external thermal environment. The temperature change of internal gas caused by the variation in the external thermal environment and wind speed will lead to a change in the shape and buoyancy of the airship, thereby affecting its flight control. The traditional static analysis method is difficult to accurately reflect this fluid-thermal-structural coupling process. In this paper, the iterative analysis method was established for the fluid-thermal-structural coupling effect of stratospheric non-rigid airship based on the models of fluid, thermal, and structural deformation. Considering the load such as the internal thermal effect and external flow field of the airship, the simulation of the thermoinduced structural deformation effect was conducted using Fluent and Abaqus software. The influence of local time and external wind speed on the structural deformation, volume, and equilibrium altitude of the airship was analyzed. The results demonstrate that, at low wind speed, the influence of aerodynamic pressure on the deformation of the airship is negligible. However, a great amount of heat is carried away by the wind, then the structural deformation caused by internal and external pressure difference is alleviated and the equilibrium altitude of the airship change obviously. This can serve as a guideline for the design and flight test of the long-endurance stratospheric nonrigid airship.

关键词： Altitude change Fluid-thermal-structural Stratospheric non-rigid air- Structural deformation Wind speed SOLAR-ARRAY PERFORMANCE OPTIMIZATION SHAPE

Hybrid Modular Smart Transformer for Asymmetrically Bidirectional Power Flow Operation

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CSEE Journal of Power and Energy Systems 2024年第4期10卷 1384-1398页

作者： Kangan Wang Youngjong Ko Rongwu Zhu Siyu wu Weimin wu Marco Liserre Shanghai Maritime University Shanghai 201306China Pukyong National University Busan 48513South Korea Harbin Institute of Technology(Shenzhen) Shenzhen 518000China Kiel University Kiel 24118Germany

The presence of renewable energy resources in LV distribution networks may lead to a distribution transformer,also known as a Smart Transformer(ST),experiencing the bidirectional power ***,the ST must have the capability to operate in both ***,the reverse power is less as compared to the forward power,thus the design of ST with the same capacity in both directions increases the hardware cost and decreases the system *** paper proposes a Hybrid-modular-ST(H-ST),composed of a mixed use of single active bridge-based series resonant converter and dual active bridge instead of complete use of uni-or bi-directional converter adopted in the conventional *** on the proposed H-ST,the impacts of power imbalance among cascaded modules in reverse operation mode are analyzed and then an effective solution based on reactive power compensation combined with the characteristics of the proposed architecture is *** simulation and experimental results clearly validate the effectiveness and feasibility of the theoretical analyses.

关键词： Cascaded H-bridge dual-active bridge series resonant converter smart transformer(ST) three-stage architecture

Designing ultrastable P2/O3-type layered oxides for sodium ion batteries by regulating Na distribution and oxygen redox chemistry

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Journal of Energy Chemistry 2024年第7期94卷 466-476页

作者： Jieyou Huang Weiliang Li Debin Ye Lin Xu Wenwei wu Xuehang wu School of Chemistry and Chemical Engineering Guangxi UniversityNanning 530004GuangxiChina Guangxi Key Laboratory for High-value Utilization of Manganese Resources Guangxi Normal University for NationalitiesChongzuo 532200GuangxiChina

P2/O3-type Ni/Mn-based layered oxides are promising cathode materials for sodium-ion batteries(SIBs)owing to their high energy ***,exploring effective ways to enhance the synergy between the P2 and 03 phases remains a ***,we design a P2/O3-type Na_(0.76)Ni_(0.31)Zn_(0.07)Mn_(0.50)Ti_(0.12)0_(2)(NNZMT)with high chemical/electrochemical stability by enhancing the coupling between the two *** the first time,a unique Na*extraction is observed from a Na-rich O3 phase by a Na-poor P2 phase and systematically *** process is facilitated by Zn^(2+)/Ti^(4+)dual doping and calcination condition regulation,allowing a higher Na*content in the P2 phase with larger Na^(+)transport channels and enhancing Na transport *** of reduced Na^(+)in the O3 phase,which increases the difficulty of H^(+)/Na^(+) exchange,the hydrostability of the O3 phase in NNZMT is considerably ***,Zn^(2+)/Ti^(4+)presence in NNZMT synergistically regulates oxygen redox chemistry,which effectively suppresses O_(2)/CO_(2) gas release and electrolyte decomposition,and completely inhibits phase transitions above 4.0 *** a result,NNZMT achieves a high discharge capacity of 144.8 mA h g^(-1) with a median voltage of 3.42 V at 20 mA g^(-1) and exhibits excellent cycling performance with a capacity retention of 77.3% for 1000 cycles at 2000 mA g^(-1).This study provides an effective strategy and new insights into the design of high-performance layered-oxide cathode materials with enhanced structure/interface stability forSIBs.

关键词： Sodium-ion batteries P2/O3-type layered oxides Na distribution Oxygen redox chemistry Hydrostability

Mechanism Design for Ancillary Service Market Considering Social Welfare and Fairness

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CSEE Journal of Power and Energy Systems 2024年第3期10卷 1000-1010页

作者： Zhi wu Yuanxi wu Wei Gu Zheng Xu Shu Zheng Jingtao Zhao School of Electrical Engineering Southeast UniversityNanjing 210096China NARI Technology Co. Ltd.Nanjing 211106China IEEE CSEE

Increasing penetration of distributed energy resources in the distribution network(DN)is threatening safe operation of the DN,which necessitates setup of the ancillary service market in the *** the ancillary service market,distribution system operator(DSO)is responsible for safety of the DN by procuring available capacities of *** existing studies,this paper proposes a novel market mechanism composed of two parts:choice rule and payment *** proposed choice rule simultaneously considers social welfare and fairness,encouraging risk-averse aggregators to participate in the ancillary service *** is then formulated as a linear programming problem,and a distributed solution using the multi-cut Benders decomposition is ***,successful implementation of the choice rule depends on each aggregator’s truthful adoption of private ***,a payment rule is also designed,which is proved to possess two properties:incentive compatibility and individual *** results demonstrate effectiveness of the proposed choice rule on improving fairness and verify properties of the payment rule.

关键词： Aggregator ancillary service market distributed mechanism fairness mechanism design

A fuse-based DC circuit breaker with vacuum interrupter enhanced by an external transverse magnetic field

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HIGH VOLTAGE 2024年第3期9卷 710-720页

作者： Xiao, Yu wu, Yi wu, Yifei Yang, Fei Rong, Mingzhe Yang, Zhuo Xi An Jiao Tong Univ Sch Elect Engn State Key Lab Elect Insulat & Power Equipment Xian Peoples R China State Grid Shaanxi Elect Power Co Ltd Xian Peoples R China

Due to the increasing power system capacity, the interruption of large fault currents has gradually become a major challenge in power systems. At the moment, such currents are interrupted mainly via circuit breakers based on the method of active current commutation. However, these types of circuit breakers tend to be costly and oversized. One possible alternative-a fuse-based circuit breaker with current commutation process enhanced by an external transverse magnetic field (ETMF)-is proposed by the authors. Its main advantage lies in the fast current commutation achieved by an ETMF-enhanced three-stage increase of the vacuum arc voltage. The study of the current commutation process is mainly represented by the authors, and the influencing factors of the current commutation-contact opening speed and ETMF current-are discussed. At last, the proposed circuit breaker is verified by an experiment, whose results show that a short-circuit current of 42 kA can be interrupted within just 2 ms.

关键词： CURRENT COMMUTATION

Imide-pillared covalent organic framework protective films as stable zinc ion-conducting interphases for dendrite-free Zn metal anodes

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Journal of Energy Chemistry 2024年第10期97卷 470-477页

作者： Xiaoman Ye Xuemei Xiao Zhijing wu Xin wu Lin Gu Sheng Liu School of Chemical Engineering and Technology Sun Yat-sen University The Key Lab of Low-Carbon Chemistry & Energy Conservation of Guangdong Province Sun Yat-sen University

The notorious growth of zinc dendrite and the water-induced corrosion of zinc metal anodes（ZMAs）restrict the practical development of aqueous zinc ion batteries（AZIBs）.In this work,a zinc metallized,imide-pillared covalent organic framework（ZPC） protective film has been engineered as a stable Zn2+ion-conducting interphase to modulate interfacial kinetics and suppress side reactions for *** to bare Zn,ZPC@Zn exhibits a higher Zn2+ionic conductivity,a larger Zn2+transference number,a lower electronic conductivity,a smaller desolvation activation energy and correspondingly a significant suppression of corrosion,hydrogen evolution and Zn ***,the ZPC@Zn||ZPC@Zn symmetric cell obtains a cycling lifespan over 3000 h under 5 mA cm-2for 1 mA h *** ZPC@Zn||NH4V4O10coin-type full battery delivers a specific capacity of 195.8 mA h g-1with a retention rate of78.5% at 2 A g-1after 1100 cycles,and the ZPC@Zn||NH4V4O10pouch full cell shows a retention of70.1% in reversible capacity at 3 A g-1after 1100 *** present incorporation of imide-linked covalent organic frameworks in the surface modification of ZMAs will offer fresh perspectives in the search for ideal protective films for the practicality of AZIBs.

关键词： Aqueous zinc ion batteries Covalent organic frameworks Imide linkage Surface modification Zinc metal anodes

RecBERT:Semantic recommendation engine with large language model enhanced query segmentation for k-nearest neighbors ranking retrieval

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Intelligent and Converged Networks 2024年第1期5卷 42-52页

作者： Richard wu the Dublin Unified School District and the SF Artificial Intelligence Club DublinCA 94568USA

The increasing amount of user traffic on Internet discussion forums has led to a huge amount of unstructured natural language data in the form of user *** modern recommendation systems rely on manual tagging,relying on administrators to label the features of a class,or story,which a user comment corresponds *** common approach is to use pre-trained word embeddings to compare class descriptions for textual similarity,then use a distance metric such as cosine similarity or Euclidean distance to find top k ***,neither approach is able to fully utilize this user-generated unstructured natural language data,reducing the scope of these recommendation *** paper studies the application of domain adaptation on a transformer for the set of user comments to be indexed,and the use of simple contrastive learning for the sentence transformer fine-tuning process to generate meaningful semantic embeddings for the various user comments that apply to each *** order to match a query containing content from multiple user comments belonging to the same class,the construction of a subquery channel for computing class-level similarity is *** channel uses query segmentation of the aggregate query into subqueries,performing k-nearest neighbors(KNN)search on each individual *** achieves state-of-the-art performance,outperforming other state-of-the-art models in accuracy,precision,recall,and F1 score for classifying comments between four and eight classes,*** outperforms the most precise state-of-the-art model(distilRoBERTa)in precision by 6.97%for matching comments between eight classes.

关键词： sentence transformer simple contrastive learning large language models query segmentation k-nearest neighbors

Principal components of nuclear mass models

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Science China(Physics,Mechanics & Astronomy) 2024年第7期67卷 65-71页

作者： Xin-Hui wu Pengwei Zhao Department of Physics Fuzhou UniversityFuzhou 350108China State Key Laboratory of Nuclear Physics and Technology School of PhysicsPeking UniversityBeijing 100871China

Principal component analysis(PCA)is employed to extract the principal components(PCs)present in nuclear mass models for the first *** effects from different nuclear mass models are reintegrated and reorganized in the extracted *** PCs are recombined to build new mass models,which achieve better accuracy than the original theoretical mass *** comparison indicates that using the PCA approach,the effects contained in different mass models can be collaborated to improve nuclear mass predictions.

关键词： nuclear mass principal component analysis nuclear models statistical methods

Drogue detection for autonomous aerial refueling via hybrid pigeon-inspired optimized color opponent and saliency aggregation

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Chinese Journal of Aeronautics 2024年第5期37卷 27-38页

作者： Tongyan wu Haibin DUAN Yanming FAN State Key Laboratory of Virtual Reality Technology and Systems School of Automation Science and Electrical EngineeringBeihang UniversityBeijing 100083China Virtual Reality Fundamental Research Laboratory Department of Mathematics and TheoriesPeng Cheng LaboratoryShenzhen 518000China AVIC Shenyang Aircraft Design and Research Institute Shenyang 110035China

Drogue detection is one of the challenging tasks in autonomous aerial refueling due to the requirement for accuracy and *** detection based on image intrinsic cues can achieve fast detection,but with poor *** studies reveal that optimization-based methods provide accurate and quick solutions for saliency *** paper presents a hybrid pigeon-inspired optimization method,the optimized color opponent,that aims to adjust the weight of color opponent channels to detect the drogue *** can optimize the weights in the selected aerial refueling scene offline,and the results are applied for drogue detection in the scene.A novel algorithm aggregated by the optimized color opponent and robust background detection is presented to provide better precision and *** results on benchmark datasets and aerial refueling images show that the proposed method successfully extracts the saliency region or drogue and exhibits superior performance against the other saliency detection methods with intrinsic *** algorithm designed in this paper is competent for the drogue detection task of autonomous aerial refueling.

关键词： Autonomous aerial refueling Drones Hybrid pigeon-inspired optimization Color opponent Saliency detection Saliency aggregation