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Multifunctional MXene/C Aerogels for Enhanced Microwave Absorption and Thermal Insulation

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纳微快报:英文版 2023年第11期15卷 74-89页

作者： Fushuo Wu Peiying Hu Feiyue Hu Zhihua Tian Jingwen Tang Peigen Zhang Long Pan michel WBarsoum Longzhu Cai ZhengMing Sun School of Materials Science and Engineering Southeast UniversityNanjing 211189People’s Republic of China Department of Materials Science&Engineering Drexel UniversityPhiladelphiaPA 19104USA The State Key Laboratory of Millimeter Waves School of Information Science and EngineeringSoutheast UniversityNanjing 210096People’s Republic of China

Two-dimensional transition metal carbides and nitrides(MXene)have emerged as promising candidates for microwave absorption(MA)***,they also have some drawbacks,such as poor impedance matching,high self-stacking tendency,and high *** tackle these challenges,MXene nanosheets were incorporated into polyacrylonitrile(PAN)nanofibers and subsequently assembled into a three-dimensional(3D)network structure through PAN carbonization,yielding MXene/C *** 3D network effectively extends the path of microcurrent transmission,leading to enhanced conductive loss of electromagnetic(EM)***,the aerogel’s rich pore structure significantly improves the impedance matching while effectively reducing the density of the MXenebased *** parameter analysis shows that the MXene/C aerogels exhibit a minimum reflection loss(RL_(min))value of−53.02 dB(f=4.44 GHz,t=3.8 mm),and an effective absorption bandwidth(EAB)of 5.3 GHz(t=2.4 mm,7.44–12.72 GHz).Radar cross-sectional(RCS)simulations were employed to assess the radar stealth effect of the aerogels,revealing that the maximum RCS reduction value of the perfect electric conductor covered by the MXene/C aerogel reaches 12.02 dB m^(2).In addition to the MA performance,the MXene/C aerogel also demonstrates good thermal insulation performance,and a 5-mm-thick aerogel can generate a temperature gradient of over 30℃ at 82℃.This study provides a feasible design approach for creating lightweight,efficient,and multifunctional MXene-based MA materials.

关键词： MXene Microwave absorption Aerogel Radar cross-sectional(RCS)simulation Thermal insulation

Novel single-ion conducting polymer electrolytes with high toughness and high resistance against lithium dendrites

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Nano Research 2023年第6期16卷 8457-8468页

作者： David Fraile-Insagurbe Nicola Boaretto Itziar Aldalur Iñigo Raposo Francisco Javier Bonilla michel Armand María Martínez-Ibañez Centre for Cooperative Research on Alternative Energies CIC energiGUNEBasque Research and Technology Alliance(BRTA)Alava Technology ParkAlbert Einstein 48Vitoria-Gasteiz 01510Spain University of the Basque Country(UPV/EHU) Barrio Sarrienas/nLeioa 48940Spain

Solid-state polymer electrolytes are considered as an alternative to classic liquid electrolytes,particularly for application in highenergy lithium metal *** respect to common dual-ion conductors,single-ion conducting polymer electrolytes(SICPEs)are less affected by lithium dendrites growth and thus are particularly interesting for application in lithium metal *** this work,novel SIC-PEs are developed,based on an ionomer having poly(ethylene-alt-maleimide)backbone and lithium phenylsulfonyl(trifluoromethanesulfonyl)imide pendant moieties,further blended with poly(ethylene oxide)(PEO)and poly(ethylene glycol)dimethyl ether(PEGDME).These SIC-PEs exhibit ionic conductivity around~7×10^(−6)S·cm^(−1) at 70℃,lithium transference number close to unity,and excellent mechanical properties,with fracture toughness over 30 J·cm^(−3).Additionally,the electrolytes show very high resistance against lithium dendrites growth,by cycling for more than 1200 h in Li°symmetric cells at a current density of 0.1 mA·cm^(−2).LiFePO4||Li°cells with these SIC-PEs were cycled at 70℃ and C/10,showing initial capacity of almost 160 mAh·g^(−1)and residual capacity of 45%after 100 *** work shows that single-ion conducting polymer electrolytes based on poly(ethylene-alt-maleimide)backbone are promising materials for application as electrolytes or catholytes in lithium metal polymer batteries.

关键词： single-ion conductors solid-state Li metal batteries polymer electrolytes lithium dendrites transference number mechanical properties

Mechanochemistry and hydrogen storage properties of 2Li_(3)N+Mg mixture

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Rare Metals 2022年第12期41卷 4223-4229页

作者： Zhi-Nian Li Hao-Chen Qiu Shu-Mao Wang Li-Jun Jiang Jun Du Jun-Xian Zhang michel Latroche Fermin Cuevas Department of Energy Materials and Technology General Research Institute for Nonferrous MetalsBeijing 100088China UMR7182 CMTR/ICMPE/CNRS-UPEC94320 Thiais CedexFrance

The Li-Mg-N-H hydrogen storage system is a promising hydrogen storage material due to its moderate operation temperature,good reversibility,and relatively high *** this work,the Li-Mg-N-H composite was directly synthesized by reactive ball milling(RBM) of Li3N and Mg powder mixture with a molar ratio of 2:1 under hydrogen pressure of 9 *** than 8.8 wt%hydrogen was absorbed during the RBM *** phases and structural evolution during the in situ hydrogenation process were analyzed by means of in situ solidgas absorption and ex situ X-ray diffraction(XRD) *** is determined that the hydrogenation can be divided into two steps,leading to mainly the formation of a lithium magnesium imide phase and a poorly crystallized amide phase,*** H-cycling properties of the as-milled composite were determined by temperature-programmed dehydrogenation(TPD) method in a closed *** onset dehydrogenation temperature was detected at 125℃,and it can reversibly desorb 3.1 wt% hydrogen under a hydrogen back pressure of 0.2 *** structural evolution during dehydrogenation was further investigated by in situ XRD *** is found that Mg(NH_(2))_(2)phase disappears at about 200 ℃,and Li_(2)Mg_(2)N_(3)H_(3),LiNH_(2),and Li_(2)MgN_(2)H_(2)phases coexist at even 300 ℃,revealing that the dehydrogenation process is step-wised and only partial hydrogen can be desorbed.

关键词： Mechanochemistry Hydrogen storage properties Li-Mg-N-H

Analytical investigation of bidirectional ductile diaphragms in multi-span bridges

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Earthquake Engineering and Engineering Vibration 2018年第2期17卷 235-250页

作者： Xiaone Wei michel Bruneau Michael Baker International ChicagoIL 60606USA Department of Civil Structuraland Environmental EngineeringUniversity at BuffaloBuffaloNY 14260USA

In the AASHTO Guide Specifications for Seismic Bridge Design Provisions,ductile diaphragms are identified as Permissible Earthquake-Resisting Elements（EREs）,designed to help resist seismic loads applied in the transverse direction of *** adding longitudinal ductile diaphragms,a bidirectional ductile diaphragm system is created that can address seismic excitations acting along both the bridge’s longitudinal and transverse *** paper investigates bidirectional ductile diaphragms with Buckling Restrained Braces（BRBs）in straight multi-span bridge with simply supported floating *** flexibility of the substructures in the transverse and longitudinal direction of the bridge is *** procedures for the bidirectional ductile diaphragms are first *** analytical model of the example bridge with bidirectional ductile diaphragms,designed based on the proposed methodology,is then built in *** and nonlinear time history analyses are performed on the bridge model,and corresponding results are *** effect of changing the longitudinal stiffness of the bidirectional ductile diaphragms in the end spans connecting to the abutment is also investigated,in order to better understand the impact on the bridge’s dynamic performance.

关键词： bidirectional ductile diaphragm seismic resistance multi-span bridge with floating spans

Conditions for Set Agreement with an Application to Synchronous Systems

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Journal of Computer Science & Technology 2009年第3期24卷 418-433页

作者： Francois Bonnet michel Raynal IRISA University of Rennes35042 Rennes CedexFrance

The k-set agreement problem is a generalization of the consensus problem： considering a system made up of n processes where each process proposes a value, each non-faulty process has to decide a value such that a decided value is a proposed value, and no more than k different values are decided. While this problem cannot be solved in an asynchronous system prone to t process crashes when t≥ k, it can always be solved in a synchronous system; [t/k]＋1 is then a lower bound on the number of rounds （consecutive communication steps） for the non-faulty processes to decide. The condition-based approach has been introduced in the consensus context. Its aim was to both circumvent the consensus impossibility in asynchronous systems, and allow for more efficient consensus algorithms in synchronous systems. This paper addresses the condition-based approach in the context of the k-set agreement problem. It has two main contributions. The first is the definition of a framework that allows defining conditions suited to the l-set agreement problem and the second is a generic synchronous k-set agreement algorithm based on conditions.

关键词： agreement problem condition efficiency lower bound synchronous system

Seismic vulnerability evaluation of axially loaded steel built-up laced members II:evaluations

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Earthquake Engineering and Engineering Vibration 2008年第2期7卷 125-136页

作者： Kangmin Lee michel Bruneau Department of Architectural Engineering Chungnam National University Department of Civil Structuraland Environmental EngineeringUniversity at BuffaloState University of New York

The test results described in Part 1 of this paper （Lee and Bruneau, 2008） on twelve steel built-up laced members （BLMs） subjected to quasi-static loading are analyzed to provide better knowledge on their seismic behavior. Strength capacity of the BLM specimens is correlated with the strength predicted by the AISC LRFD Specifications. Assessments of hysteretic properties such as ductility capacity, energy dissipation capacity, and strength degradation after buckling of the specimen are performed. The compressive strength of BLMs is found to be relatively well predicted by the AISC LRFD Specifications. BLMs with smaller kl/r were ductile but failed to reach the target ductility of 3.0 before starting to fracture, while those with larger kl/r could meet the ductility demand in most cases. The normalized energy dissipation ratio, EC/ET and the normalized compressive strength degradation, Cr″/Cr of BLMs typically decrease as normalized displacements δ/δb,exp increase, and the ratios for specimens with larger kl/r dropped more rapidly than for specimens with smaller kl/r; similar trends were observed for the monolithic braces. The BLMs with a smaller slenderness ratio, kl/r, and width-to-thickness ratio, b/t, experienced a larger number of inelastic cycles than those with larger ratios.

关键词： seismic vulnerability built-up compression member strength capacity ductility capacity energy dissipation strength degradation

Solid-state electrolytes for safe rechargeable lithium metal batteries:a strategic view

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Materials Futures 2023年第3期2卷 114-137页

作者： Leire Meabe Itziar Aldalur Simon Lindberg MikelArrese-Igor michel Armand Maria Martinez-Ibanez Heng Zhang Centre for Cooperative Research on Alternative Energies(CIC energiGUNE)Basque Research and Technology Alliance(BRTA) 01510 Vitoria-GasteizSpain University of the Basque Country(UPV/EHU) Barrio Sarrienas/n48940 LeioaSpain Key Laboratory of Material Chemistry for Energy Conversion and Storage(Ministry of Education) School of Chemistry and Chemical EngineeringHuazhong University of Science and TechnologyWuhan

Despite the efforts devoted to the identification of new electrode materials with higher specific capacities and electrolyte additives to mitigate the well-known limitations of current lithium-ion batteries,this technology is believed to have almost reached its energy density *** suffers also of a severe safety concern ascribed to the use of flammable liquid-based *** this regard,solid-state electrolytes(SSEs)enabling the use of lithium metal as anode in the so-called solid-state lithium metal batteries(SSLMBs)are considered as the most desirable solution to tackle the aforementioned *** emerging technology has rapidly evolved in recent years thanks to the striking advances gained in the domain of electrolyte materials,where SSEs can be classified according to their core chemistry as organic,inorganic,and hybrid/composite *** strategic review presents a critical analysis of the design strategies reported in the field of SSEs,summarizing their main advantages and disadvantages,and providing a future perspective toward the rapid development of SSLMB technology.

关键词： solid-state electrolytes lithium metal batteries polymer electrolytes safe batteries inorganic solid electrolyte hybrid electrolyte composite electrolyte

Ahlfors-regular curves and Carleson measures

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Science China Mathematics 2020年第6期63卷 1057-1064页

作者： Huaying Wei michel Zinsmeister Department of Mathematics and Statistics Jiangsu Normal UniversityXuzhou 21116China IDP Universite d'OrleansOrleans 45067France

We study the relation between the boundary of a simply connected domainΩbeing Ahlfors-regular and the invariance of Carleson measures under the push-forward operator induced by a conformal mapping from the unit disk△onto the domainΩ.As an application,we characterize the chord-arc curves with small norms and the asymptotically smooth curves in terms of the complex dilatation of some quasiconformal reflection with respect to the curve.

关键词： Ahlfors-regular curve Carleson measure push-forward operator chord-arc curve asymptotically smooth curve

Simulation of unconventional well tests with the finite volume method

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Petroleum Science 2012年第3期9卷 317-329页

作者： CANCELLIERE michel VERGA Francesca Politecnico di Torino DITAGTorino (TO) 10129 Italy

The finite volume method has been successfully applied in several engineering fields and has shown outstanding performance in fluid dynamics simulation. In this paper, the general framework for the simulation ofnear-wellbore systems using the finite volume method is described. The mathematical model and the numerical model developed by the authors are presented and discussed. A radial geometry in the vertical plane was implemented so as to thoroughly describe near-wellbore phenomena. The model was then used to simulate injection tests in an oil reservoir through a horizontal well and proved very powerful to correctly reproduce the transient pressure behavior. The reason for this is the robustness of the method, which is independent of the gridding options because the discretization is performed in the physical space. The model is able to describe the phenomena taking place in the reservoir even in complex situations, i.e. in the presence of heterogeneities and permeability barriers, demonstrating the flexibility of the finite volume method when simulating non-conventional tests. The results are presented in comparison with those obtained with the finite difference numerical approach and with analytical methods, if possible.

关键词： Finite volume method numerical methods horizontal well modeling injection testing gridding