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Enhancing energy storage density of poly(arylene ether nitrile)via incorporating modified barium titanate nanorods and hotstretching

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Nano Research 2024年第8期17卷 7574-7584页

作者： Zhengjiao Zhang Lingyun zhou Lingling Wang Qingqing hao Xiufu Hua Renbo wei School of Chemical Engineering Northwest UniversityXi’an 710069China Yangtze Delta Region Institute Tsinghua UniversityJiaxing 314006China

Dielectric energy storage materials that are extensively employed in capacitors and other electronic devices have attracted increasing attentions amid the rapid progress of electronic ***,the commercialized polymeric and ceramic dielectric materials characterized by low energy storage density face numerous limitations in practical *** this study,we report the simultaneous enhancement of dielectric properties of poly(arylene ether nitrile)(PEN)through the incorporating of sulfonated PEN(SPEN)modified barium titanate nanorods(BTNR)(SPEN@BTNR)and *** is synthesized using a two-step hydrothermal method,aminated with KH550,and then reacted with SPEN to form the cladding-modified SPEN@*** to the intrinsic high permittivity of barium titanate(BT)and enhanced compatibility between SPEN@BTNR and PEN stemming from the cladding of SPEN,the dielectric constant and breakdown strength of SPEN@BTNR/PEN composite are as high as 14.0 at 103 Hz and 198.1 kV/mm at the doping amount of 15 wt.%,*** a result,the energy storage density of SPEN@BTNR/PEN is increased to 2.43 J/cm^(3),compared with that of 0.82 J/cm^(3)for *** addition,derived from the rearrangement of SPEN@BTNR and orientation of PEN after hot-stretching,the dielectric constant and breakdown strength of SPEN@BTNR/PEN with 15 wt.%fillers are further enhanced to 17.1 and 204.8 kV/mm,respectively,resulting in an energy storage density of 3.36 J/cm^(3).The boosting of energy storage density up to 310%provides a new idea for improving the performances of dielectric energy storage materials.

关键词： barium titanate nanorods poly(arylene ether nitrile) dielectric constant breakdown strength energy density

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Effect of CO_(2) Opposing Multiple Jets on Thermoacoustic Instability and NO_(x) Emissions in a Lean-Premixed Model Combustor

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Journal of Thermal Science 2024年第1期33卷 207-221页

作者： zhou hao HU Liubin Institute for Thermal Power Engineering State Key Laboratory of Clean Energy UtilizationZhejiang UniversityHangzhou 310027China

This paper experimentally studied the effect of CO_(2) opposing multiple jets on the thermoacoustic instability and NO_(x) emissions in a lean-premixed model *** feasibility was verified from three variables:the CO_(2) jet flow rate,hole numbers,and hole diameters of the *** indicate that the control effect of thermoacoustic instability and NO_x emissions show a reverse trend with the increase of open area ratio on the whole,and the optimal jet flow rate range is 1-4 L/min with CO_(2) opposing multiple *** this flow rate range,the amplitude and frequency of the dynamic pressure and heat release signals CH~* basically decrease as the CO_(2) flow rate increases,which avoids high-frequency and high-amplitude thermoacoustic *** amplitude-damped ratio of dynamic pressure and CH*can reach as high as 98.75% and 93.64% with an optimal open area ratio of 3.72%.NO_(x) emissions also decrease as the jet flow rate increases,and the maximum suppression ratio can reach 68.14%.Besides,the flame shape changes from a steep inverted "V" to a more flat "M",and the flame length will become shorter with CO_(2) opposing multiple *** research achieved the synchronous control of thermoacoustic instability and NO_(x) emissions,which could be a design reference for constructing a safer and cleaner combustor.

关键词： thermoacoustic instability lean-premixed model combustor CO_(2)opposing multiple jets open area ratio NO_(x)emissions

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A hybrid physics-informed data-driven neural network for CO_(2) storage in depleted shale reservoirs

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Petroleum Science 2024年第1期21卷 286-301页

作者： Yan-wei Wang Zhen-Xue Dai Gui-Sheng Wang Li Chen Yu-zhou Xia Yu-hao zhou College of Construction Engineering Jilin UniversityChangchun130026JilinChina Institute of Intelligent Simulation and Early Warning for Subsurface Environment Jilin UniversityChangchun130026JilinChina School of Energy Resources China University of GeosciencesBeijing100083China Department of Safety Environmental Protection and Quality ManagementShengli OilfieldSinopecDongying257000ShandongChina Key Laboratory of Thermo-Fluid Science and Engineering of MOE School of Energy and Power EngineeringXi'an Jiaotong UniversityXi'an710049ShaanxiChina College of Computer Science and Technology China University of Petroleum(East China)Qingdao266580ShandongChina Department of Physics University of FribourgFribourg1700Switzerland

To reduce CO_(2) emissions in response to global climate change,shale reservoirs could be ideal candidates for long-term carbon geo-sequestration involving multi-scale transport ***,most current CO_(2) sequestration models do not adequately consider multiple transport ***,the evaluation of CO_(2) storage processes usually involves laborious and time-consuming numerical simulations unsuitable for practical prediction and *** this paper,an integrated model involving gas diffusion,adsorption,dissolution,slip flow,and Darcy flow is proposed to accurately characterize CO_(2) storage in depleted shale reservoirs,supporting the establishment of a training *** this basis,a hybrid physics-informed data-driven neural network(HPDNN)is developed as a deep learning surrogate for prediction and *** incorporating multiple sources of scientific knowledge,the HPDNN can be configured with limited simulation resources,significantly accelerating the forward and inversion ***,the HPDNN can more intelligently predict injection performance,precisely perform reservoir parameter inversion,and reasonably evaluate the CO_(2) storage capacity under complicated *** validation and test results demonstrate that the HPDNN can ensure high accuracy and strong robustness across an extensive applicability range when dealing with field data with multiple noise *** study has tremendous potential to replace traditional modeling tools for predicting and making decisions about CO_(2) storage projects in depleted shale reservoirs.

关键词： Deep learning Physics-informed data-driven neural network Depleted shale reservoirs CO_(2)storage Transport mechanisms

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Enhancing SAEAs with unevaluated solutions:a case study of relation model for expensive optimization

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Science China(Information Sciences) 2024年第2期67卷 41-58页

作者： hao hao Xiaoqun ZHANG Aimin zhou Institute of Natural Sciences Shanghai Jiao Tong University Shanghai Frontiers Science Center of Molecule Intelligent Syntheses School of Computer Science and Technology East China Normal University

Surrogate-assisted evolutionary algorithms(SAEAs) hold significant importance in resolving expensive optimization problems. Extensive efforts have been devoted to improving the efficiency of SAEAs through the development of proficient model-assisted solution selection methods, which, however, first requires generating high-quality solutions. The fundamental paradigm of evaluating a limited number of solutions in each generation within SAEAs reduces the variance of adjacent populations, thereby affecting the quality of offspring solutions. This is a frequently encountered issue yet receives little attention. To address the issue, this paper presents a framework using unevaluated solutions to enhance the efficiency of *** surrogate model is employed to identify high-quality solutions for the direct generation of new solutions without evaluation. To ensure dependable selection, we have introduced two tailored relation models to select the optimal solution and the unevaluated population. A comprehensive experimental analysis is performed on two test suites, which showcases the superiority of the relation model over regression and classification models in the solution selection phase. Furthermore, the surrogate-selected unevaluated solutions with high potential have been shown to enhance the efficiency of the algorithm significantly.

关键词： expensive optimization unevaluated solutions relation model surrogate-assisted evolutionary algorithm

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K doping stabilizes three-dimensional K0.2Na1.3Mn0.5O2-δ as high-performance cathode for sodium-ion batteries

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Rare Metals 2024年第10期43卷 5030-5038页

作者： Jia-hao Xu You-Huan Zhu wei-Min Yang Hua Cheng zhou-Guang Lu Industrial Training Center Shenzhen Polytechnic University Department of Materials Science and Engineering Southern University of Science and Technology School of Materials Science and Environmental Engineering Shenzhen Polytechnic University

It is a difficult challenge to simultaneously employ the cationic and anionic redox chemistry in cathode materials for sodium-ion batteries with high *** though layered oxides （classified as two-dimensional oxides） demonstrate excellent promise in the high discharge capacity,their poor oxygen transformation via redox reactions is limited by crystal ***,a doping strategy was conceived to tackle this issue and increase redox efficiency.K doping was applied to transform the two-dimensional Na1.3Mn0.7O2（NMO） to threedimensional K0.2Na1.3Mn0.5O2（KNMO）,preventing the irreversible phase shift and preserving the crystal structure’s stability while *** this modification treatment,KNMO features manganese and oxygen reactive sites,delivering a promising energy density of 190mAh·g-1at 5 mA·g-1in the 2.0–4.5 V voltage range (vs71.4 mAh·g-1for the pristine NMO).Moreover,it displays improved capacity retention of more than 83.5% after 50cycles at 50 mA·*** results demonstrated that doped intercalation oxides were promising for redox oxygen transformation in sodium-ion batteries.

关键词： High-performance cathode Metal ion dopings Sodium-ion batteries Three-dimensional structure

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Numerical study on local failures of reinforced concrete slabs against underwater close-in explosions

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第8期25卷 650-669页

作者： Fei zhou Hedong LI hao WU College of Civil Engineering Tongji UniversityShanghai 200092China School of Civil Engineering and Architecture Zhejiang Sci-Tech UniversityHangzhou 310018China

Reinforced concrete(RC)slabs are the primary load-carrying member of underwater *** can suffer severe local failures such as cratering,spalling,or breaching as a result of underwater close-in(UWCI)*** this study,we established a fully validated high-fidelity finite element analysis approach to precisely reproduce the local failures of RC slabs after a UWCI explosion.A recently proposed dynamic constitutive model is used to describe wet *** effects of free water content on the material properties,including the tensile/compressive strength,elastic modulus,strain rate effect,failure strength surface,and equation of state,are comprehensively calibrated based on existing test *** calibrated material parameters are then verified by a single-element test.A high-fidelity finite element analysis(FEA)approach of an RC slab subjected to a UWCI explosion is established using an arbitrary Lagrangian-Eulerian(ALE)*** previous UWCI explosion tests on RC orifice targets and underwater contact explosion tests on saturated concrete slabs showed that the established FEA approach could accurately reproduce the pressure-time history in water and damage patterns,including the cracking,cratering,and spalling,of the RC orifice target and saturated concrete ***,parametric studies conducted by simulating an RC slab subjected to a UWCI explosion showed that:(i)the local failure of an RC slab enlarges with increased charge weight,reduced standoff distance,and reduced structural thickness;(ii)compared to a water-backed RC slab,an air-backed RC slab exhibits much more obvious local and structural ***,to aid the anti-explosion design of relevant underwater facilities,based on over 90 simulation cases empirical formulae are summarized to predict local failure modes,i.e.,no spall,spall,and breach,of water-and air-backed RC slabs subjected to a UWCI explosion.

关键词： Reinforced concrete slab(RC) Underwater close-in(UWCI)explosion Saturated concrete Failure modes Numerical simulation

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Investigation on UV-curing Reprocessable Thermosets Bearing Hindered Urea Bonds and Their Composites with Modified Zinc Oxide Nanoparticles

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Chinese Journal of Polymer Science 2024年第6期42卷 751-765页

作者： Jun-hao zhou Li-Ming Tang Key Laboratory of Advanced Materials of Ministry of Education of China Department of Chemical EngineeringTsinghua UniversityBeijing100084China

In this study,a series of hindered urea bond(HUB)containing polyurethane-urea methacrylate prepolymers and a none HUB containing polyurethane methacrylate prepolymer were prepared using isobornyl methacrylate as the reactive diluent via one-pot *** prepolymers were characterized fully by various ***,their thermosets were fabricated via UV curing in presence of a photo initiator,and their mechanical property and thermal behavior were investigated and *** from the none HUB containing thermoset,the HUB containing thermosets(defined as PUT)could be recycled and reprocessed by hot press under relatively mild conditions with high recovery ratio of mechanical ***,zinc oxide(ZnO)nanoparticles were modified with 3-(trimethoxysilyl)propyl methacrylate and the modified ZnO(defined as ZnO-TPM)was dispersed and polymerized into PUT matrix to prepare their *** influence of ZnO-TPM on the mechanical performance of the composites was evaluated,which indicated that the Young’s modulus and tensile strength increased gradually to the maximum values at ZnO-TPM content of 1 wt%and then *** composites also displayed good reprocessability with improved recovery ratio compared to the pure PUT *** addition,the composite materials exhibited strong UV absorption capacity,implying their potential application in the circumstance where UV-shielding was required.

关键词： Polyurethane-urea methacrylate Hindered urea bond ZnO nanoparticles Reprocessing UV curing

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A review on adhesion behavior of chip seal pavement and aggregate

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Journal of Traffic and Transportation Engineering(English Edition) 2024年第3期11卷 441-466页

作者： Yuming zhou Zhuyi Peng Jinyu Wang Jianguo wei hao Liu Di Wang Jinming Li Key Laboratory of Road Structure and Material of Ministry of Transport(Changsha) Changsha University of Science and TechnologyChangsha 410114China School of Traffic and Transportation Engineering Changsha University of Science and TechnologyChangsha 410114China Wuhan Huike Testing Co. Ltd.Wuhan 430000China Department of Civil Engineering University of OttawaON KIN 6N5Canada CCCC Infrastructure Maintenance Group Co. Ltd.Beijing 100102China

Chip seal is widely used for preventive maintenance to mitigate pavement deterioration,but it is prone to aggregate loss during pavement *** further promote the development and application of chip seals in road engineering in China,the research progress of the adhesion behavior of aggregate and binder in chip seals was reviewed in this paper,focusing on the adhesion mechanism of emulsified asphalt and alkaline *** Influencing factors and evaluation methodology of chip seals'aggregate adhesion behavior were also *** results demonstrate that the adhesion process between emulsified asphalt and alkaline aggregate is divided into three processes including infiltration,demulsification,and cluster,which is more complicated when compared to hot *** designing a chip seal,not only the characteristics of single material should be paid attention to,but also the combination of binder and aggregate matters a *** form good adhesion between aggregate and asphalt binder,various influencing factors such as material selection,design method,and construction technical index should be considered comprehensively in the whole design,construction,and operation *** methods for evaluating adhesion behavior are summarized,including macroscopic adhesion performance tests,image analysis technology,and model *** is not objective to evaluate the aggregate adhesion behavior of chip seal only by a single evaluation method.A comprehensive evaluation based on the micro-macro multi-scale method should be considered in the future.

关键词： Chip seal Adhesion behavior Asphalt binder Aggregate

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Formation of free-surface vortex and vortex suppression by rotating stopper-rod at end of tundish casting

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Journal of Iron and Steel Research International 2024年第5期31卷 1104-1116页

作者： Qing Fang Peng Zhao Hua Zhang Wen-hao zhou Gang Yu Jia-hui Wang Hong-wei Ni The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan430081HubeiChina Hunan Valin Xiangtan Iron and Steel Co. Ltd.Xiangtan411101HunanChina Hubei Provincial Key Laboratory for New Processes of Ironmaking and Steelmaking Wuhan University of Science and TechnologyWuhan430081HubeiChina

A rotating stopper-rod technique was proposed to suppress the formation of free-surface vortex in the *** large eddy simulation model coupled with volume of fluid model was developed to study the steel–slag–gas three-phase flow *** critical slag entrapment height of the free-surface vortex and mass of residual steel were predicted at different rotating speeds(30,60,90 and 120 r/min)of the rotating *** numerical model was verified by water model *** results showed that by rotating the stopper-rod in the opposite direction of the vortex above the submerged entry nozzle,the formation of vortex can be effectively disturbed and the critical height of the free-surface vortex can be *** for the 2nd strand,when the rotating speeds are 30,60,90 and 120 r/min,the critical height of the free-surface vortex above the 2nd strand is 7.3,4.7,6.3 and 7.4 cm,respectively.A reasonable rotating speed should be 60 r/min,which can reduce about 2 tons of residual *** rotating speeds just can reduce about 1.6 tons of residual steel.

关键词： Tundish Free-surface vortex Stopper-rod Numerical simulation Multiphase flow

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Joint UAV trajectory and communication design with heterogeneous multi-agent reinforcement learning

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Science China(Information Sciences) 2024年第3期67卷 225-245页

作者： Xuanhan zhou Jun XIONG Haitao Zhao Xiaoran LIU Baoquan REN Xiaochen ZHANG Jibo wei hao YIN College of Electronic Science and Technology National University of Defense Technology Systems Engineering Institute Academy of Military Sciences PLA

Unmanned aerial vehicles(UAVs) are recognized as effective means for delivering emergency communication services when terrestrial infrastructures are unavailable. This paper investigates a multiUAV-assisted communication system, where we jointly optimize UAVs’ trajectories, user association, and ground users(GUs)’ transmit power to maximize a defined fairness-weighted throughput metric. Owing to the dynamic nature of UAVs, this problem has to be solved in real time. However, the problem’s non-convex and combinatorial attributes pose challenges for conventional optimization-based algorithms, particularly in scenarios without central controllers. To address this issue, we propose a multi-agent deep reinforcement learning(MADRL) approach to provide distributed and online solutions. In contrast to previous MADRLbased methods considering only UAV agents, we model UAVs and GUs as heterogeneous agents sharing a common objective. Specifically, UAVs are tasked with optimizing their trajectories, while GUs are responsible for selecting a UAV for association and determining a transmit power level. To learn policies for these heterogeneous agents, we design a heterogeneous coordinated QMIX(HC-QMIX) algorithm to train local Q-networks in a centralized manner. With these well-trained local Q-networks, UAVs and GUs can make individual decisions based on their local observations. Extensive simulation results demonstrate that the proposed algorithm outperforms state-of-the-art benchmarks in terms of total throughput and system fairness.

关键词： unmanned aerial vehicle (UAV) trajectory design resource allocation multi-agent deep reinforcement learning (MADRL) heterogeneous agents

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