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Comparison of tailpipe carbonyls and volatile organic compounds emissions from in-use gasoline/CNG bi-fuel vehicles

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Journal of Environmental Sciences 2024年第1期135卷 619-629页

作者： Jiachen Li Yunshan Ge Xin Wang Mengzhu Zhang Haohao Wang School of Mechanical Engineering Beijing Institute of TechnologyBeijing 100081China

Ground-level ozone contamination has been globally an urban air quality issue,particularly for China,which has recently made significant progress in purifying its *** exhaust emissions from motor vehicles,predominantly carbonyls and volatile organic compounds(VOCs),are among the leading contributors to ozone *** this chassislevel study,the unregulated emissions from five China-5 certified gasoline/CNG bi-fuel taxis,along with their ozone forming potential(OFP),were *** is found that carbonyls and VOCs were mainly emitted during the starting phase no matter the engine was cold or *** to gasoline,CNG fueling reduced VOCs emissions on a large scale,especially in the starting phase,but had elevated *** a fleet average,CNG fueling derived 15%and 46%less OFP than gasoline in cold-and hot-start tests,*** contributed to over 90%of the total OFP of the *** terms of alleviating ground-level ozone contamination,CNG is a feasible alternative to gasoline on light-duty vehicles.

关键词： CNG Gasoline Carbonyls VOCs OFP

Investigations of the mechanical response of dummy HTPB propellant grain under ultrahigh acceleration overload conditions using onboard flight-test measurements

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Defence Technology（防务技术） 2024年第2期32卷 473-484页

作者： Yiming Zhang Ningfei Wang Weihua Ma Ran Wang Long Bai Yi Wu School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China beijing System Design institute of Electro-mechanic Engineering Beijing 100854China Xi'an Changfeng Research institute of Mechanism and Electricity Xi'an 710065China

In this paper,to study the mechanical responses of a solid propellant subjected to ultrahigh acceleration overload during the gun-launch process,specifically designed projectile flight tests with an onboard measurement system were *** projectiles containing dummy HTPB propellant grains were successfully recovered after the flight tests with an ultrahigh acceleration overload value of 8100 *** onboard-measured time-resolved axial displacement,contact stress and overload values were successfully obtained and *** compression tests of the dummy HTPB propellant used in the gunlaunched tests were carried out at low and intermediate strain rates to characterize the propellant's dynamic properties.A linear viscoelastic constitutive model was employed and applied in finite-element simulations of the projectile-launching *** the launch process,the dummy propellant grain exhibited large deformation due to the high acceleration overload,possibly leading to friction between the motor case and propellant *** calculated contact stress showed good agreement with the experimental results,though discrepancies in the overall displacement of the dummy propellant grain were *** dynamic mechanical response process of the dummy propellant grain was analysed in *** results can be used to estimate the structural integrity of the analysed dummy propellant grain during the gun-launch process.

关键词： Gun-launched flight test Dummy HTPB propellant Onboard measurements Utrahigh overload Mechanical response

Molecular Dynamics Simulation of Shock Response of CL-20 Co-crystals Containing Void Defects

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Defence Technology（防务技术） 2024年第1期31卷 364-374页

作者： Changlin Li Wei Yang Qiang Gan Yajun Wang Lin Liang Wenbo Zhang Shuangfei Zhu Changgen Feng State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China School of Materials Science&Engineering Beijing Institute of TechnologyBeijing 100081China

To investigate the effect of void defects on the shock response of hexanitrohexaazaisowurtzitane(CL-20)co-crystals,shock responses of CL-20 co-crystals with energetic materials ligands trinitrotoluene(TNT),1,3-dinitrobenzene(DNB),solvents ligands dimethyl carbonate(DMC) and gamma-butyrolactone(GBL)with void were simulated,using molecular dynamics method and reactive force *** is found that the CL-20 co-crystals with void defects will form hot spots when impacted,significantly affecting the decomposition of molecules around the *** degree of molecular fragmentation is relatively low under the reflection velocity of 2 km/s,and the main reactions are the formation of dimer and the shedding of nitro *** existence of voids reduces the safety of CL-20 co-crystals,which induced the sensitivity of energetic co-crystals CL-20/TNT and CL-20/DNB to increase more *** has occurred under the reflection velocity of 4 km/s,energetic co-crystals are easier to polymerize than solvent co-crystals,and are not obviously affected by *** results show that the energy of the wave decreases after sweeping over the void,which reduces the chemical reaction frequency downstream of the void and affects the detonation performance,especially the solvent co-crystals.

关键词： CL-20 co-crystals Molecular dynamics simulation Reactive forcefield Impact response Hot spot Void defect

Strong-coupling superconductivity with Tc above 70 K in Be-decorated monolayer T-graphene

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Science China(Physics,Mechanics & Astronomy) 2024年第1期67卷 99-105页

作者： Liu Yang Peng-Fei Liu Hao-Dong Liu Ya-Ping Li Na Jiao Hong-Yan Lu Bao-Tian Wang Ping Zhang School of Physics and Physical Engineering Qufu Normal UniversityQufu 273165China institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China Spallation Neutron Source Science Center Dongguan 523803China institute of Applied Physics and Computational mathematics Beijing 100088China

Using first-principles calculations,we predict a new type of two-dimensional(2D)beryllium(Be)-decorated T-graphene named BeC_(2),where Be atoms are inserted into C–C bonds linking the carbon tetrarings of *** band structure shows that BeC_(2)is metallic,thus,the possible phonon-mediated superconductivity is explored based on the Eliashberg *** calculated electron-phonon coupling(EPC)constantλis up to 4.07,and the corresponding superconducting critical temperature(Tc)is 72.1 K,approaching the liquid nitrogen *** reason for the high Tc is the strong *** it is proved to be an anisotropic single-gap superconductor by analyzing the superconducting gap?kof BeC_(2).The electronic susceptibility calculation shows strong nesting effect in BeC_(2).Since rare 2D superconductors show such a strong EPC constantλwhich originates from the coupling between electrons in C-pzorbital and in-plane vibrations of Be and C atoms,the predicted BeC_(2)provides a new platform for investigating strong EPC 2D superconductor.

关键词： two-dimensional carbon-based superconductor electron-phonon coupling strong coupling high superconducting critical temperature

Special issue on system identiﬁcation and estimation

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Control Theory and Technology 2024年第2期22卷 147-148页

作者： Weixing Zheng Tianshi Chen Chengpu Yu Wenxiao Zhao Western Sydney University SydneyAustralia The Chinese University of Hong Kong ShenzhenChina beijing institute of Technology BeijingChina The Academy of mathematics and Systems Science Chinese Academy of SciencesBeijingChina

It is our great pleasure and honor to organize this special issue“System Identiﬁcation and Estimation”.System identiﬁcation has been a surprisingly lively and resilient area of research in the control community for many *** grew out of statisticians’interest in time series analysis beginning in the 1940s and became a“regular control topic”in the 1960s,as indicated by theﬁrst IFAC Symposium on System Identiﬁcation held in Prague,Czech Republic,in *** years later,it is still an important area of research in theﬁeld of *** is relevant to ask why the interest in system identiﬁcation has remained so *** answer might be that more and more applications in engineering require mathematical models and the combined use of system identiﬁcation and physical modeling is the basic way to obtain reliable *** special issue is focusing on the latest development,trends,and novel methods for system identiﬁcation and estimation and these contributions will give interesting and inspiring insights into the current status of the area.

关键词： estimation system IFAC

Anti-aging performance improvement and enhanced combustion efficiency of boron via the coating of PDA

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Defence Technology（防务技术） 2024年第3期33卷 399-410页

作者： Shuai Ma Qinghai Shu Mengyang Zhang Hongyu Huang Yansong Shi Xijuan Lv Shuai Zhao School of Materials Science and Engineering Beijing Institute of TechnologyBeijing100081China Key Lab of Advanced Optoelectronic Quantum Architecture and Measurement(MOE) Beijing Key Lab of Nanophotonics&Ultrafine Optoelectronic SystemsSchool of PhysicsBeijing Institute of TechnologyBeijing100081China Tangshan Research institute of beijing institute of Technology Tangshan063000HebeiChina

Boron is an ambitious fuel in energetic materials since its high heat release values,but its application is prohibited by low combustion efficiency and oxidization during *** polydopamine(PDA)was introduced into boron particles,investigating the impact of PDA content on the energetic behavior of *** results indicated that the PDA coating formed a fishing net structure on the surface of boron *** heat release results showed that the combustion calorific value of B@PDA was higher than that of the raw ***,the actual combustion heat of boron powder in B@10%PDA increased by 38.08%.Meanwhile,the DSC peak temperature decreased by 100.65℃under similar oxidation rate compared to raw ***,the B@PDA@AP and B@AP composites were prepared,and their combustion properties were *** was demonstrated that B@10%PDA@AP exhibited superior performance in terms of peak pressure and burning time,*** peak pressure is 12.43 kPa more than B@AP and burning time is 2.22 times higher than B@***,the coating of PDA effectively inhibits the oxidization of boron during storage and enhances the energetic behavior of boron and corresponding composites.

关键词： Boron particles Polydopamine Anti-aging performance improvement Heat release

Effects of projectile parameters on the momentum transfer and projectile melting during hypervelocity impact

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Defence Technology（防务技术） 2024年第2期32卷 89-103页

作者： Wenjin Liu Qingming Zhang Renrong Long Zizheng Gong Ren Jiankang Xin Hu Siyuan Ren Qiang Wu Guangming Song State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081China beijing institute of Spacecraft Environment Engineering China Academy of Space TechnologyBeijing100094China

The effects of projectile/target impedance matching and projectile shape on energy,momentum transfer and projectile melting during collisions are investigated by numerical *** comparing the computation results with the experimental results,the correctness of the calculation and the statistical method of momentum transfer coefficient is *** shapes of aluminum,copper and heavy tungsten alloy projectiles striking aluminum,basalt,and pumice target for impacts up to 10 km/s are *** influence mechanism of the shape of the projectile and projectile/target density on the momentum transfer was *** an increase in projectile density and length-diameter ratio,the energy transfer time between the projectile and targets is *** projectile decelerates slowly,resulting in a larger cratering *** energy consumed by the projectile in the excavation stage increased,resulting in lower mass-velocity of ejecta and momentum transfer *** numerical simulation results demonstrated that for different projectile/target combinations,the higher the wave impedance of the projectile,the higher the initial phase transition velocity and the smaller the mass of phase *** results can provide theoretical guidance for kinetic impactor design and material selection.

关键词： Hypervelocity impact Energy partitioning Impact melting Momentum transfer

Lithiophilic Li-Si alloy-solid electrolyte interface enabled by high-concentration dual salt-reinforced quasi-solid-state electrolyte

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Journal of Energy Chemistry 2024年第8期95卷 216-230,I0005页

作者： Yuanxing Zhang Ling Zhang Zhiguang Zhao Yuxiang Zhang Jingwen Cui Chengcai Liu Daobin Mu Yuefeng Su Borong Wu Feng Wu School of Materials Science and Engineering Beijing Institute of TechnologyBeijing 100081China Chongqing Innovation Center Beijing Institute of TechnologyChongqing 401120China Collaborative Innovation Center of Electric Vehicles in beijing Beijing 100081China

Solid polymer electrolytes(SPEs)are urgently required to achieve practical solid-state lithium metal batteries(LMBs)and lithium-ion batteries(LIBs),Herein,we proposed a mechanism for modulating interfacial conduction and anode interfaces in high-concentration SPEs by *** electrolyte exhibits superior ionic conductivity and remarkable interface compatibility with salt-rich clusters:(1)polymer-plastic crystal electrolyte(P-PCE,TPU-SN matrix)dissociates ion pairs to facilitate Li+transport in the electrolyte and regulates Li^(+)diffusion in the *** crosslinking structure of the matrix compensates for the loss of mechanical strength at high-salt concentrations;(2)dual-anion TFSI^(-)_(n)-DFBOP^(-)_(m)in the Li^(+)solvation sheath facilitates facile Li^(+)desolvation and formation of salt-rich clusters and is conducive to the formation of Li conductive segments of TPU-SN matrix;(3)theoretical calculations indicate that the decomposition products of LiDFBOP form SEI with lower binding energy with LiF in the SN system,thereby enhancing the interfacial electrochemical redox kinetics of SPE and creating a solid interface SEI layer rich in *** a result,the optimized electrolyte exhibits an excellent ionic conductivity of9.31×10^(-4)S cm^(-1)at 30℃and a broadened electrochemical stability up to 4.73 *** designed electrolyte effectively prevents the formation of Li dendrites in Li symmetric cells for over 6500 h at0.1 mA cm^(-2).The specific Li-Si alloy-solid state half-cell capacity shows 711.6 mAh g^(-1)after 60 cycles at 0.3 A g^(-1).Excellent rate performance and cycling stability are achieved for these solid-state batteries with Li-Si alloy anodes and NCM 811 *** 811‖Prelithiated silicon-based anode solid-state cell delivers a discharge capacity of 195.55 mAh g^(-1)and a capacity retention of 97.8%after 120 *** 811‖Li solid-state cell also delivers capacity retention of 84.2%after 450 cycles.

关键词： Prelithiation Li-Si alloy anode Solid-state electrolyte SEI layer

Metal-organic frameworks and their composites for advanced lithium-ion batteries:Synthesis,progress and prospects

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Journal of Energy Chemistry 2024年第2期89卷 449-470,I0011页

作者： Chengcai Liu Borong Wu Tao Liu Yuanxing Zhang Jingwen Cui Lingjun Huang Guoqiang Tan Ling Zhang Yuefeng Su Feng Wu School of Material Science and Engineering Beijing Institute of TechnologyBeijing 100081China Chonging Innovation Center Beijing Institute of TechnologyChongqing 401120China Collaborative Innovation Center of Electric Vehicles in beijing Beijing 100081China

Metal-organic frameworks(MOFs)are among the most promising materials for lithium-ion batteries(LIBs)owing to their high surface area,periodic porosity,adjustable pore size,and controllable chemical *** instance,their unique porous structures promote electrolyte penetration,ions transport,and make them ideal for battery *** the chemical composition of MOF can introduce more active sites for electrochemical ***,MOFs and their related composites have been extensively and thoroughly explored for ***,the reported reviews solely include the applications of MOFs in the electrode materials of LIBs and rarely involve other aspects.A systematic review of the application of MOFs in LIBs is essential for understanding the mechanism of MOFs and better designing related MOFs battery *** review systematically evaluates the latest developments in pristine MOFs and MOF composites for LIB applications,including MOFs as the main materials(anode,cathode,separators,and electrolytes)to auxiliary materials(coating layers and additives for electrodes).Furthermore,the synthesis,modification methods,challenges,and prospects for the application of MOFs in LIBs are discussed.

关键词： Metal-organic frameworks Electrodes Electrolytes Separators Lithium-ion batteries