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Decreasing the CTE of Thermoplastic Polyimide by Blending with a Thermosetting System

Chinese Journal of Polymer science 2023年第6期41卷 956-961,I0010页

作者： Yu-Cheng Zi Gao-Jie Wu Dong-Xu Pei Shu Guo Sheng-Li Qi Guo-Feng Tian De-Zhen Wu Key Laboratory of Carbon Fiber and Functional Polymers(Beijing University of Chemical Technology) Ministry of EducationBeijing 100029 China Institute of Analysis and Testing Beijing Academy of Science and Technology(Beijing Center For Physical&Chemical Analysis)Beijing 100089China

A series of thermoplastic polyimide resins with a low coefficient of thermal expansion(CTE)were prepared by blending a rigid resin system 3,3’,4,4’-biphenyltetracarboxylic dianhydride(BPDA)/p-phenylenediamine(PDA)with a flexible resin system 4,4’-[isopropylidenebis(pphenyleneoxy)]diphthalic anhydride(BPADA)/*** effects of the blending ratio on the macromolecular coil size,free volume,and CTE of the mixed system were *** mixing is carried out in the prepolymer poly(amide acid)(PAA)stage,which makes the two systems more compatible and is conducive to the formation of a semi-interpenetrating network structure between the rigid molecular chains and flexible molecular *** flexible structure of the BPADA/PDA system is used to ensure the melt processing *** rigid characteristics of the BPDA/PDA system can inhibit the movement of molecular chains and reduce the free volume fraction,thereby reducing the CTE *** the rigid system content reaches 30%,the CTE can be reduced to 38 ppm/*** method provides a new approach for studying low CTE thermoplastic polyimide resins.

关键词： value. system chains

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Tailoring the proximity of iron and manganese atomic sites for efficient CO_(2)electroreduction reaction

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Nano Research 2025年第3期18卷 73-81页

作者： Xiaohui Sun Bangyan Zhang Qing Lu Jingjing Jiang Chenliang Ye Guoqing Cui Zechao Zhuang Jun Zhang Johannes HBitter Guanna Li Chunming Xu State Key Laboratory of Heavy Oil Processing China University of Petroleum(Beijing)Beijing 102249China Department of Chemistry Tsinghua UniversityBeijing 100084China Biobased Chemistry and Technology Wageningen University&ResearchWageningen6708WGThe Netherlands Department of Materials Science and Engineering China University of Petroleum(East China)Qingdao 266580China Institute of Analysis and Testing Institute of Analysis and TestingBeijing Academy of Science and Technology(Beijing Center for Physical and Chemical Analysis)Beijing 100094China

Electrochemical carbon dioxide reduction reaction(CO_(2)RR)into high-value added chemicals and fuels has aroused wide attention,but suffers from high overpotential and poor ***,nitrogen-doped carbon supported Fe and Mn heteronuclear single atom catalysts with different Fe and Mn inter-site distance were fabricated via a templating isolation approach and tested for CO_(2)RR to CO in an aqueous *** catalyst with atomically dispersed Fe and Mn sites in close proximity exhibited the highest CO_(2)RR performance,with a CO Faradaic efficiency of 96%at a low overpotential of 320 mV,and a Tafel slope of only 62 mV·dec^(−1),comparable to state-of-the-art gold *** analysis combined with theory highlighted that single Mn atom at the neighboring site of Fe enhanced the electronic localization of Fe center,which facilitated the generation of key^(*)COOH intermediate as well as CO^(*) desorption on Fe,leading to superior CO_(2)RR performance at low *** work offers atomic-level insights into the correlation between the inter-site distance of atomic sites and CO_(2)RR performance,and paves a new avenue for precise control of single-atom sites on carbon surface for highly active and selective electrocatalysts.

关键词： CO_(2)electroreduction heteronuclear single-atom catalyst inter-site distance electron localization scaling relationships low overpotentials

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analysis of Conjoint Response in Post-stroke Patients Using the Attention-coupled Weighting Method

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Machine Intelligence Research 2025年第2期22卷 352-367页

作者： Jingyao Chen Chen Wang Ningcun Xu Zeng-Guang Hou Liang Peng Pu Zhang Faculty of Innovation Engineering CASIA-MUST Joint Laboratory of Intelligence Science and TechnologyMacao University of Science and TechnologyMacao 999078China State Key Laboratory of Multimodal Artificial Intelligence Systems Institute of AutomationChinese Academy of SciencesBeijing 100190China Institute of Analysis and Testing Beijing Academy of Science and TechnologyBeijing 100089China Department of Rehabilitation Evaluation China Rehabilitation Research CenterBeijing 100068China

Rehabilitation assessment plays a vital role in the recovery process of post-stroke ***,many studies have focused on the implementation of automated assessment ***,the impact of stroke on the synergistic pattern between different human joints is not well *** this study,we developed an attention-coupled weighting based quantitative analysis model to identify the pathological alteration in the conjoint response structure between stroke patients and healthy participants,thus providing more intrinsic suggestions for the post-stroke rehabilitation *** collaboration with the China Rehabilitation Research Center and the Macao University of science and technology,we recruited 15 post-stroke patients and 15 healthy participants to complete several actions selected from the Fugl-Meyer assessment(FMA)scale,which is a commonly used post-stroke rehabilitation assessment scale in clinical *** study proposed an attentional coupling weight(ACW)extraction *** filtering the weights in the attentional coupling network using a priori matrix,we can analyse the effect of stroke on the alteration of synergistic structures and the coordination patterns of the upper and lower ***,we used a commonly accepted synergy analysis method,the nonnegative matrix decomposition(NMF)method,for comparison and *** experimental results demonstrated the effectiveness of our method in quantifying the synergistic structure pattern alterations in post-stroke patients,which provides a new targeted option for the rehabilitation process.

关键词： Intelligent assessment conjoint response attentional coupling network spatio-temporal weight extraction.

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Synergy enhancement of Co single atoms and asymmetric subnanoclusters for Fenton-like activation

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Nano Research 2024年第9期17卷 7935-7944页

作者： Ming Ma Zhiyi Sun Ziwei Deng Xiang Li Fang Zhang Wenxing Chen School of Materials Key Laboratory of Cluster Science Ministry of EducationBeijing Key Laboratory of Photoelectronic/Electrophotonic Conversion MaterialsAdvanced Technologies Research Institute(Jinan)Advanced Research Institute of Multidisciplinary ScienceSchool of Chemistry and Chemical EngineeringBeijing Institute of TechnologyBeijing 100081China Energy and Catalysis Center School of Materials Science and EngineeringBeijing Institute of TechnologyBeijing 100081China Analysis and Testing Center Beijing Institute of TechnologyBeijing Institute of TechnologyBeijing 100081China

As a new water treatment technology,Fenton-like reaction has great *** this study,we successfully prepared an excellent Fenton-like catalyst,which is composed of cobalt monoatoms and asymmetric subnanoclusters(labeled CoSA/Clu-C_(2)N),and exhibits excellent peroxymonosulfate(PMS)activation *** directly comparing the catalytic properties of CoSA-C_(2)N and CoSA/Clu-C_(2)N,the synergistic effects of coasymmetric Co subclusters and Co atoms on the activation of PMS and degradation of organic micropollutants were *** results showed that CoSA/Clu-C_(2)N had higher degradation rates of carbamazepine(CBZ),antipyrine(AT)and chlorobenzoic acid(CA)when combined with active oxidant *** cyclic frequency of CBZ was 5.4 min^(-1),which was twice as high as the catalytic constant of CoSA-C_(2)N(2.4 min^(-1)).The results show that CoSA/Clu-C_(2)N cobalt subnanoclusters and cobalt single atom can synergistically improve the catalytic performance of activated PMS oxidation of micropollutants in *** addition,electron paramagnetic resonance(EPR)technology has proved that the introduction of Co subnano clusters in CoSA/Clu-C_(2)N is conducive to the production of singlet oxygen(1O_(2)),thereby improving the efficiency of pollutant *** work lays a solid foundation for the future design of advanced multifunctional catalysts by carefully regulating and combining monmetallic atoms and metal subnanoclusters.

关键词： carbamazepine Fenton-like reaction Co single atoms asymmetrical sub-nanoclusters peroxymonosulfate synergy enhancement

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In an Ocean or a River:Bilinear Auto-Backlund Transformations and Similarity Reductions on an Extended Time-Dependent(3+1)-Dimensional Shallow Water Wave Equation

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China Ocean Engineering 2025年第1期39卷 160-165页

作者： GAO Xin-yi College of Science and Beijing Key Laboratory on Integration and Analysis of Large-Scale Stream DataNorth China University of TechnologyBeijing 100144China Beijing Laboratory of New Energy Storage Technology Beijing Municipal Education CommissionBeijing 102206China

With respect to oceanic fluid dynamics,certain models have appeared,e.g.,an extended time-dependent(3+1)-dimensional shallow water wave equation in an ocean or a river,which we investigate in this *** symbolic computation,we find out,on one hand,a set of bilinear auto-Backlund transformations,which could connect certain solutions of that equation with other solutions of that equation itself,and on the other hand,a set of similarity reductions,which could go from that equation to a known ordinary differential *** results in this paper depend on all the oceanic variable coefficients in that equation.

关键词： ocean river extended time-dependent(3+1)-dimensional shallow water wave equation bilinear auto-Bäcklund transformation similarity reduction symbolic computation

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IncEFL:a sharing incentive mechanism for edge-assisted federated learning in industrial IoT

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Digital Communications and Networks 2025年第1期11卷 106-115页

作者： Jiewei Chen Shaoyong Guo Tao Shen Yan Feng Jian Gao Xuesong Qiu State Key Laboratory of Networking and Switching Technology Beijing University of Post and TelecommunicationsBeijing 100087China Kunming University of Science and Technology Kunming 650031China Yunnan Provincial Academy of Science and Technology Kunming 650228China

As the information sensing and processing capabilities of IoT devices increase,a large amount of data is being generated at the edge of Industrial IoT(IIoT),which has become a strong foundation for distributed Artificial Intelligence(AI)***,most users are reluctant to disclose their data due to network bandwidth limitations,device energy consumption,and privacy *** address this issue,this paper introduces an Edge-assisted Federated Learning(EFL)framework,along with an incentive mechanism for lightweight industrial data *** order to reduce the information asymmetry between data owners and users,an EFL model-sharing incentive mechanism based on contract theory is *** addition,a weight dispersion evaluation scheme based on Wasserstein distance is *** study models an optimization problem of node selection and sharing incentives to maximize the EFL model consumers'profit and ensure the quality of training *** incentive-based EFL algorithm with individual rationality and incentive compatibility constraints is ***,the experimental results verify the effectiveness of the proposed scheme in terms of positive incentives for contract design and performance analysis of EFL systems.

关键词： Federated learning Data sharing Edge intelligence Incentives Contract theory

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Dynamic mechanical behavior and nonlinear hyper-viscoelastic constitutive model of SiO_(2) particle-reinforced silicone rubber composite:experimental and numerical investigation

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Acta Mechanica Sinica 2024年第6期40卷 100-114页

作者： Xihuang Zhang Xuexing Wu He Yang Ying Chen Xiangli Cheng Bo Liu Hui Zhao Institute of Electronic Engineering China Academy of Engineering PhysicsMianyang621999China State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081China

SiO_(2)-particle reinforced silicon rubber composite(SP-RSRC)is a widely utilized material that offers shock absorption protection to various engineering structures in impact *** paper presents a comprehensive investigation of the mechanical behavior of SP-RSRC under various strain rates,employing a combination of experimental,theoretical,and numerical ***,quasi-static and dynamic compression tests were performed on SP-RSRC utilizing a universal testing machine and split Hopkinson pressure bar(SHPB)*** stress-strain relationships of SP-RSRC were obtained for strain rates ranging from 1×10^(−3) to 3065 s^(−1).The results indicated that the composite showed evident strain rate sensitivity,along with ***,a nonlinear visco-hyperelastic constitutive model was developed,consisting of a hyperelastic component utilizing the 3rd-order Ogden energy function and a viscous component employing a rate-dependent relaxation time *** model accurately characterized the dynamic mechanical response of SP-RSRC,effectively mitigating the challenge of calibrating an excessive number of material parameters inherent in conventional viscoelastic ***,the simplified rubber material(SRM)model,integrated within the LS-DYNA software,was chosen to depict the mechanical properties of SP-RSRC in numerical *** parameters of the SRM model were further calibrated based on the strain-stress relationships of SP-RSRC,as predicted by the developed nonlinear visco-hyperelastic constitutive ***,an inverse ballistic experiment using a single-stage air gun was conducted for *** simulations of SHPB experiments and the inverse ballistic experiment were then performed,and the reliability of the calibrated SRM model was verified by comparing the results of experiments and numerical *** study offers a valuable reference for the utilization of SP-RSRC in the realm of impact protection.

关键词： Silicone rubber composites Dynamic mechanical properties Nonlinear visco-hyperelastic constitutive model Inverse ballistic experiment

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Resist Thermal Shock Through Viscoelastic Interface Encapsulation in Perovskite Solar Cells

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Energy & Environmental Materials 2024年第6期7卷 238-245页

作者： Sai Ma Jiahong Tang Guizhou Yuan Ying Zhang Yan Wang Yuetong Wu Cheng Zhu Yimiao Wang Shengfang Wu Yue Lu Shumeng Chi Tinglu Song Huanping Zhou Manling Sui Yujing Li Qi Chen Beijing Key Laboratory of Construction Tailorable Advanced Functional Materials and Green Applications MIIT Key Laboratory for Low-dimensional Quantum Structure and DevicesExperimental Center of Advanced MaterialsSchool of Materials Science and EngineeringBeijing Institute of TechnologyBeijing 100081China Beijing Key Laboratory of Microstructure and Properties of Solids College of Materials Science and EngineeringBeijing University of TechnologyBeijing 100124China Analysis and Testing Center Jiangnan UniversityWuxi 214122China School of Materials Science and Engineering Peking UniversityBeijing 100871China

Enhancing the lifetime of perovskite solar cells(PSCs)is one of the essential challenges for their *** the external encapsulation protects the perovskite device from the erosion of moisture and oxygen under various harsh ***,the perovskite devices still undergo static and dynamic thermal stress during thermal and thermal cycling aging,respectively,resulting in irreversible damage to the morphology,component,and phase of stacked ***,the viscoelastic polymer polyvinyl butyral(PVB)material is designed onto the surface of perovskite films to form flexible interface *** PVB interface encapsulation,the surface modulus of perovskite films decreases by nearly 50%,and the interface stress range under the dynamic temperature field(−40 to 85°C)drops from−42.5 to 64.8 MPa to−14.8 to 5.0 ***,PVB forms chemical interactions with FA+cations and Pb^(2+),and the macroscopic residual stress is regulated and defects are reduced of the PVB encapsulated perovskite *** a result,the optimized device's efficiency increases from 22.21%to 23.11%.Additionally,after 1500 h of thermal treatment(85°C),1000 h of damp heat test(85°C&85%RH),and 250 cycles of thermal cycling test(−40 to 85°C),the devices maintain 92.6%,85.8%,and 96.1%of their initial efficiencies,respectively.

关键词： device stability perovskite solar cells stress field surface modulus thermal shock

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Fatigue failure analysis and heat treatment strategy optimization of torsion bar spring for automobile suspension system used in light vehicles

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Journal of Iron and Steel Research International 2025年第3期32卷 799-811页

作者： Jia-xing Liu Yong-jin Wu Chao-lei Zhang Wan-li Sun Wen-bin Ding Shuai-jun Dong Institute for Carbon Neutrality School of Materials Science and EngineeringUniversity of Science and Technology BeijingBeijing100083China State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing100083China Institute of Steel Sustainable Technology Liaoning Academy of MaterialsShenyang110167LiaoningChina

The failure analysis was conducted on unqualified torsion bar spring in automobile suspension system used for light vehicles during engine *** effects of through hardening,surface induction hardening,quenching and tempering,and tempering temperature on the microstructure and fatigue life of 45CrNiMoVA steel torsion bars were also *** showed that only the torsion bar spring after through quenching and tempering is subjected to surface induction quenching and tempering to achieve the fatigue life of the qualified torsion *** fatigue life of torsion bar spring reaches 3×10^(5) cycles more than the required 2×10^(5) *** is because the distribution of gradient microstructure was helpful to relieve the applied stress during the fatigue *** microstructure of the non-hardened region,which consists of tempered sorbite regardless of whether it is tempered at 330 or 430℃,contributes to minimizing the impact of temper brittleness on the fatigue life of the torsion ***,the fatigue life of the torsion bar is relatively unaffected by temper brittleness due to the presence of tempered sorbite in its non-hardened *** the reason for the unqualified fatigue life was that the depth and hardness of the hardened region did not meet the standard requirements of 5–7 mm and 47–52 HRC,respectively.

关键词： Fatigue life Torsion bar Tempering temperature 45CrNiMoVA steel Fracture

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How do high-voltage cathode and PEO electrolyte get along well?EIS analysis mechanism&potentiometric control strategy

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Journal of Energy Chemistry 2024年第9期96卷 424-436页

作者： Xiaodong Bai Chaoliang Zheng Heng Zhang Jian Liu Panpan Wang Baojia Xia Jianling Li State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China Shanghai Institute of Microsystem and Information Technology Chinese Academy of SciencesShanghai 201800China

PEO-based all-solid-state electrolytes are extensively utilized and researched owing to their exceptional safety,low-mass-density,and ***,the low oxidation potential of PEO makes the interface problem with the high-voltage cathode extremely *** this work,the impedance of PEO-based all-solid-state batteries with high-voltage cathode(NCM811)was studied at different *** Nyquist plots displayed a gyrate arc at low-frequencies for NCM811/PEO *** on the kinetic modeling,it was deduced that there is a decomposition reaction of PEO-matrix in addition to de-embedded reaction of NCM811,and the PEO intermediate product(dehydra-PEO)adsorbed on the electrode surface leading to low-frequency inductive ***,the distribution of relaxation time shows the dehydra-PEO results in the kinetic tardiness of the charge transfer process in the temporal ***,an artificial interface layer(CEI_(x))was modified on the surface of NCM811 to regulate the potential of cathode/electrolyte interface to prevent the high-voltage deterioration of ***/CEI_(x)/PEO batteries exhibit capacity retentions of 96.0%,84.6%,and 76.8%after undergoing 100 cycles at cut-off voltages of 4.1,4.2,and 4.3 V,***,here the failure mechanism of high-voltage PEO electrolyte is investigated by EIS and a proposed solving strategy is presented.

关键词： PEo-based electrolyte High-voltage cathode Electrochemical impedance spectroscopy Mechanism research Electrochemical characteristic

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