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Bed inventory balance and stability of dual circulating fluidized bed systems

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Particuology 2024年第1期84卷 98-106页

作者： Yangjun wei Leming Cheng David Pallares Bo Leckner Institute for Thermal Power Engineering State Key Laboratory of Clean Energy UtilizationZhejiang UniversityHangzhou310027China Department of space Earth and EnvironmentChalmers University of TechnologyS-41296GöteborgSweden

Experiments and modelling are conducted for general understanding on the imbalance phenomenon and for discussion on the strategies to improve the bed inventory balance and stability of a dual circulating fluidized bed(DCFB)*** experiments are carried out in a 15.5 m high pilot-scale DCFB cold test system.A fluid-dynamic DCFB model is developed based on a 1.5-dimensional semi-empirical model of an industrial CFB boiler,validated by experimental *** effects of control methods and operation conditions on the bed inventory balance and on the stability of the pilot-and large-scale DCFB systems are discussed.A"stable-unbalanced"state,where the system reaches a steady state,consisting of un-balanced bed inventories,is observed in both experiments and model *** maintain a balanced state and similar bed inventory in the DCFB systems with similar cross-sectional areas,it is recom-mended to keep similar total pressure drops or gas velocities in both reactors.

关键词： Bed inventory balance stability Dual circulating fluidized bed(DCFB) Experiment Modelling

series Reports from Professor wei's Group of Chongqing University:Advancements in Electrochemical Energy Conversions(1/4):Report 1:High-performance Oxygen Reduction Catalysts for Fuel Cells

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电化学（中英文） 2024年第7期30卷 1-27页

作者： Fa-Dong Chen Zhuo-Yang Xie Meng-Ting Li si-Guo Chen wei Ding Li Li Jing Li Zi-Dong wei state Key Laboratory of Advanced Chemical Power sources(Chongqing University) College of Chemistry and Chemical EngineeringChongqing UniversityChongqing400044China

Two major challenges,high cost and short lifespan,have been hindering the commercialization process of lowtemperature fuel *** wei's group has been focusing on decreasing cathode Pt loadings without losses of activity and durability,and their research advances in this area over the past three decades are briefly reviewed *** the Pt-based catalysts and the low Pt usage,they have firstly tried to clarify the degradation mechanism of Pt/C catalysts,and then demonstrated that the activity and stability could be improved by three strategies:regulating the nanostructures of the active sites,enhancing the effects of support materials,and optimizing structures of the three-phase *** Pt-free catalysts,especialiy carbon-based ones,several strategies that they proposed to enhance the activity of nitrogen-/heteroatom-doped carbon catalysts are firstly ***,an indepth understanding of the degradation mechanism for carbon-based catalysts is discussed,and followed by the corresponding stability enhancement ***,the carbon-based electrode at the micrometer-scale,faces the challenges such as low active-site density,thick catalytic layer,and the effect of hydrogen peroxide,which require rational structure design for the integral cathodic *** review finally gives a brief conclusion and outlook about the low cost and long lifespan of cathodic oxygen reduction catalysts.

关键词： Fuel cell Oxygen reduction reaction Pt-based catalyst Carbon-based catalyst

The Existence of a Meridional Curve in Closed Incompressible surfaces in Fully Alternating Link Complements

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Chinese Annals of Mathematics,series B 2024年第1期45卷 73-80页

作者： wei LIN school of Mathematical sciences Dalian University of TechnologyDalian 116024LiaoningChina

Menasco showed that a closed incompressible surface in the complement of a non-split prime alternating link in s^(3) contains a circle isotopic in the link complement to a meridian of the *** on this result,he was able to argue the hyperbolicity of non-split prime alternating links in *** et *** that if F■s×I\L is an essential torus,then F contains a circle which is isotopic in s×I\L to a meridian of *** author generalizes his result as follows:Let s be a closed orientable surface,L be a fully alternating link in s×I\If F ■ s×I\L is a closed essential surface,then F contains a circle which is isotopic in s×I\L to a meridian of L.

关键词： Fully alternating Incompressible surfaces Meridionally incompressible

Zeros of Complete symmetric Polynomials over Finite Fields

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Journal of systems science & Complexity 2024年第4期37卷 1772-1788页

作者： CAO wei school of Mathematics and statistics Minnan Normal UniversityZhangzhou 363000China

Wan and Zhang(2021) obtained a nontrivial lower bound for the number of zeros of complete symmetric polynomials over finite fields,and proposed a problem whether their bound can be *** this paper,the author improves Wan-Zhang's bound from three *** proposed results are based on the estimates related to the number of certain permutations and the value sets of non-permutation polynomials associated to the complete symmetric *** the author believes that there are still possibilities to improve the bounds and hence Wan-Zhang's bound.

关键词： Complete symmetric polynomial finite field permutation polynomial value set

High-sensitivity formaldehyde gas sensor based on Ce-doped urchin-like snO_(2) nanowires derived from calcination of sn-MOFs

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Frontiers of Materials science 2024年第1期18卷 29-43页

作者： wei Xiao wei Yang shantang Liu Hubei Key Lab of Novel Reactor&Green Chemical Technology School of Chemistry and Environmental EngineeringWuhan Institute of TechnologyWuhan 430073China Hubei Key Laboratory of Wudang Local Chinese Medicine Research Department of ChemistrySchool of Pharmaceutical SciencesHubei University of MedicineShiyan 442000China

Metal-organic frameworks(MOFs)have attracted widespread attention due to their regular structures,multiple material centers,and various *** are always considered as one kind of ideal templates for developing highly sensitive and selective gas *** this study,the advantages of MOFs with the high specific surface area(71.9891 m^(2)·g^(-1))and uniform morphology were fully utilized,and urchin-like snO_(2) nanowires were obtained by the hydrothermal method followed by the calcination using sn-MOFs consisting of the ligand of C_(9)H_(6)O_(6)(H_(3)BTC)and sn/Ce center ions as sacrificial *** unique urchin-like nanowire structure facilitated gas diffusion and adsorption,resulting in superior gas sensitivity.A series of Ce-doped snO_(2) nanowires with different doping ratios were synthesized,and their gas sensing properties towards formaldehyde were *** resulted Ce-snO_(2) was revealed to have high sensitivity(201.2 at 250℃),rapid response(4 s),long-term stability,and good repeatability for formaldehyde sensing,and the gas sensing mechanism of Ce-snO_(2) exposed to formaldehyde was also systematically discussed.

关键词： Ce-snO_(2) snO_(2) gas sensor formaldehyde sn-MOF

Risk Constrained self-scheduling of AA-CAEs Facilities in Electricity and Heat Markets:A Distributionally Robust Optimization Approach

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CsEE Journal of Power and Energy systems 2024年第3期10卷 1159-1167页

作者： Zhiao Li Laijun Chen wei wei shengwei Mei Department of Electrical Engineering Tsinghua UniversityBeijing 100084China New Energy(Photovoltaic)Industry Research Center Qinghai UniversityXining 810016China IEEE

Advanced adiabatic compressed air energy storage(AA-CAEs)has the advantages of large capacity,long service time,combined heat and power generation(CHP),and does not consume fossil fuels,making it a promising storage technology in a low-carbon *** appropriate self-scheduling model can guarantee AA-CAEs’s profit and attract ***,very few studies refer to the cogeneration ability of AA-CAEs,which enables the possibility to trade in the electricity and heat markets at the same *** this paper,we propose a multimarket self-scheduling model to make full use of heat produced in *** volatile market price is modeled by a set of inexact distributions based on historical data through-***,the self-scheduling model is cast as a robust risk constrained program by introducing stackelberg game theory,and equivalently reformulated as a mixed-integer linear program(MILP).The numerical simulation results validate the proposed method and demonstrate that participating in multienergy markets increases overall *** impact of uncertainty parameters is also discussed in the sensibility analysis.

关键词： Advanced adiabatic compressed air energy storage(AA-CAEs) conditional value at risk(CVaR) distributionally robust optimization(DRO) heat market self-scheduling stackelberg game

Robot-Oriented 6G satellite-UAV Networks: Requirements, Paradigm shifts, and Case studies

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China Communications 2024年第2期21卷 74-84页

作者： Peng wei wei Feng Yunfei Chen Ning Ge wei Xiang Department of Electronic Engineering Tsinghua UniversityBeijing 100084China Department of Engineering University of DurhamDH13LEDurhamUK school of Computing Engineering and Mathematical SciencesLa Trobe UniversityMelbourneVIC 3086Australia

Networked robots can perceive their surroundings, interact with each other or humans,and make decisions to accomplish specified tasks in remote/hazardous/complex environments. satelliteunmanned aerial vehicle(UAV) networks can support such robots by providing on-demand communication services. However, under traditional open-loop communication paradigm, the network resources are usually divided into user-wise mostly-independent links,via ignoring the task-level dependency of robot collaboration. Thus, it is imperative to develop a new communication paradigm, taking into account the highlevel content and values behind, to facilitate multirobot operation. Inspired by Wiener’s Cybernetics theory, this article explores a closed-loop communication paradigm for the robot-oriented satellite-UAV network. This paradigm turns to handle group-wise structured links, so as to allocate resources in a taskoriented manner. It could also exploit the mobility of robots to liberate the network from full coverage,enabling new orchestration between network serving and positive mobility control of robots. Moreover,the integration of sensing, communications, computing and control would enlarge the benefit of this new paradigm. We present a case study for joint mobile edge computing(MEC) offloading and mobility control of robots, and finally outline potential challenges and open issues.

关键词： closed-loop communication mobility control satellite-UAV network structured resource allocation

A Quantitative seismic Topographic Effect Prediction Method Based upon BP Neural Network Algorithm and FEM simulation

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Journal of Earth science 2024年第4期35卷 1355-1366页

作者： Qifeng Jiang Mianshui Rong wei wei Tingting Chen shandong seismic Hazard Prevention Center Shandong Earthquake AgencyJinan250014China shandong Institute of Earthquake Engineering Jinan250021China Key Laboratory of Urban security and Disaster Engineering of China Ministry of Education Beijing University of TechnologyBeijing100124China Publicity and Education Center Shandong Earthquake AgencyJinan250014China shandong Earthquake station Shandong Earthquake AgencyJinan250014China

Topography can strongly affect ground motion,and studies of the quantification of hill surfaces’topographic effect are relatively *** this paper,a new quantitative seismic topographic effect prediction method based upon the BP neural network algorithm and three-dimensional finite element method(FEM)was *** FEM simulation results were compared with seismic records and the results show that the PGA and response spectra have a tendency to increase with increasing elevation,but the correlation between PGA amplification factors and slope is not obvious for low *** BP neural network models were established for the prediction of amplification factors of PGA and response *** kinds of input variables’combinations which are convenient to achieve are proposed in this paper for the prediction of amplification factors of PGA and response spectra,*** absolute values of prediction errors can be mostly within 0.1 for PGA amplification factors,and they can be mostly within 0.2 for response spectra’s amplification *** input variables’combination can achieve better prediction performance while the other one has better expandability of the predictive ***,the BP models only employ one hidden layer with about a hundred nodes,which makes it efficient for training.

关键词： seismic topographic effect finite element method BP neural network algorithm earthquake disaster prevention

A condition-based maintenance policy for reconfigurable multi-device systems

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Advances in Manufacturing 2024年第2期12卷 252-269页

作者： shu-Lian Xie Feng Xue wei-Min Zhang Jia-wei Zhu school of Mechanical Engineering Tongji UniversityShanghai201804People’s Republic of China

The exploration of component states for optimizing maintenance schedules in complex systems has garnered significant interest from ***,current literature usually overlooks the critical aspects of system flexibility and *** implementation of system reconfiguration can effectively mitigate system downtime and enhance production *** study proposes a dynamic condition-based maintenance policy considering reconfiguration for reconfigurable systems.A double-layer decision rule was constructed for the devices and *** achieve the best overall maintenance effect of the system,the remaining useful life probability distribution and recommended maintenance time of each device were used to optimize the concurrent maintenance time window of the devices and determine whether to reconfigure them.A comprehensive maintenance efficiency index was introduced that simultaneously considered the maintenance cost rate,reliability,and availability of the system to characterize the overall maintenance *** reconfiguration cost was included in the maintenance *** proposed policy was tested through numerical experiments and compared with different-level *** results show that the proposed policy can significantly reduce the downtime and maintenance costs and improve the overall system reliability and availability.

关键词： Condition-based maintenance(CBM) Reconfigurable system Remaining useful life Maintenance cost system reliability