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Theoretical and numerical research on the dynamic launch response of carbon fiber composite cartridges

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Defence Technology（防务技术） 2024年第3期33卷 426-436页

作者： Ruijie zhang hui Xu Chenlei Huang kun Liu Zhilin wu School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing 210094JiangsuChina

Understanding the dynamic response of composite material cartridges during the firing process is of great significance for improving their reliability and safety.A theoretical model describing the dynamic response of composite material cartridges is established based on the thick-walled cylinder theory and rate-dependent constitutive model of composite *** correctness of the theoretical model is validated through finite element simulations of cartridge *** influence of chamber pressure and cartridge wall thickness on the cartridge's deformation process and stress distribution is *** results indicate that the primary deformation of composite material cartridges inside the chamber is elastic *** to metal cartridges,composite material cartridges require higher pressure for touching-chamber and are more prone to developing gaps after unloading to ensure smooth *** the deformation process,the touching-chamber behavior of the cartridge can improve the stress *** the same chamber pressure,the touching-chamber behavior can reduce the circumferential stress by approximately 30%.The inner wall surface of the cartridge is a critical area that requires *** touching-chamber behavior can be facilitated by appropriately reducing the cartridge wall thickness while ensuring overall *** study can provide guidance for the optimization design of composite material cartridges.

关键词： Composite material cartridges Dynamic response Thick-walled cylinder theory Finite element simulation Toughing-chamber behavior

Assessing the energy release characteristics during the middle detonation reaction stage of aluminized explosives

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Defence Technology（防务技术） 2024年第3期33卷 270-277页

作者： kun Yang Lang Chen Danyang Liu bin zhang Jianying Lu Junying wu State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China

Afterburning behind the detonation front of an aluminized explosive releases energy on the millisecond timescale,which prolong the release of detonation energy and the energy release at different stages also shows significant ***,at present,there are few effective methods for evaluating the energy release characteristics of the middle reaction stage of such explosives,which can have a duration of tens to hundreds of *** present work demonstrates an approach to assessing the midstage of an aluminized explosive detonation based on a water push test employing a high degree of *** this method,the explosive is contained in a steel cylinder having one end closed that is installed at the bottom of a transparent water *** detonation,the gaseous products expand in one direction while forcing water ahead of *** resulting underwater shock wave and the interface between the gas phase products and the water are tracked using an ultra-high-speed framing and streak *** shock wave velocity in water and the expansion work performed by the gaseous detonation products were calculated to assess the energy release characteristics of aluminized explosives such as CL-20 and RDX in the middle stage of the detonation *** the middle stage of the detonation process of these aluminized explosives,the aluminum reaction reduced the attenuation of shock waves and increased the work performed by gas phase products.A higher aluminum content increased the energy output while the presence of oxidants slowed the energy release *** work demonstrates an effective means of evaluating the performance of aluminized explosives.

关键词： Aluminized explosive Non-ideal detonation Water push test Energy release

Photoredox-Catalyzed Metal-Free Regio-&Stereoselective C(sp^(2))-H Amination of Enamides with N-Aminopyridium Salts

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Chinese Journal of Chemistry 2024年第18期42卷 2235-2242页

作者： Zheng-Bao Qin kun Ni Li Wang Xiao-di wu Yu zhang Kai Zhao Institute of Advanced Synthesis School of Chemistry and Molecular EngineeringJiangsu National Synergetic Innovation Center for Advanced MaterialsNanjing Tech UniversityNanjingJiangsu211816China college of Chemical Engineering Nanjing Forestry UniversityNanjingJiangsu 210037China

A visible-light-induced photoredox-catalyzed regioselective and stereoselective C(sp')-H amination of enamides with bench-stable and A visible-light-induced photoredox-catalyzed regioselective and stereoselective C(sp)-H amination of enamides with bench-stable and easily accessible N-aminopyridium salts is developed,affording synthetically and biologically prominent vicinal 1,2-diamine scaffolds with broad substrate scope and excellent functional group *** transformation proceeded through a radical pathway involving the Giese addition of the relatively electrophilic N-centered sulfonamidyl radical species to nucleophilicβ-olefinic position of enamides followed by the ensuing single electron oxidation andβ-H elimination,delivering geometrically-defined Z-configuredβ-sulfonamidylated *** operational simplicity,environmental friendliness and cost efficiency of this methodology allowed it to pave a new avenue to enrich the arsenal of synthetically crucial functionalized enamides and their related derivatives.

关键词： Enamides Amination Photoredox catalysis Regioselective Stereoselective Metal-free

Ultralow-phase-noise and broadband frequency-hopping coupled optoelectronic oscillator under quiet point operation

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Photonics Research 2024年第8期12卷 1785-1793页

作者： hui LIU MINGYANG GUO TIAN zhang JIAN DAI kun XU State Key Laboratory of Information Photonics and Optical Communications Beijing University of Posts and TelecommunicationsBeijing 100876China School of Electronic Engineering Beijing University of Posts and TelecommunicationsBeijing 100876China

Advancements in microwave photonics have yielded novel approaches for generating high-purity microwave *** these,optoelectronic oscillators(OEOs)and coupled optoelectronic oscillators(COEOs)have demonstrated the capability to generate frequency-independent microwaves with exceptionally low phase ***,the tunability of the oscillators is rather limited due to the necessity for narrowband electronic bandpass filters,presenting challenges in achieving both wide and rapid tuning ***,we present a COEO featuring ultralow phase noise,flexible tuning capability,and high *** is achieved through a quiet point(QP)-operated harmonic mode-locked fiber laser,which effectively mitigates optical amplifier noise and supermode competition,thus significantly diminishing the necessity for ultra-narrow electronic *** to the liberated tuning ability,we present an oscillator that can be tuned from 2 GHz to 18 GHz,with phase noise as low as-140 d Bc/Hz at 10 k Hz under the QP *** then illustrate the practical application of the proposed oscillator in generating frequency-hopping signals with consistent spurious modes less than-85 d Bc,absolute phase noise below-135 d Bc/Hz at 10 k Hz,hopping resolution of 1.25 MHz,and fractional frequency stability below 6.1×10^(-12)at 1 s averaging time when locked to a *** presented COEO structure emerges as a compelling solution for agile and low-noise microwave sources in advanced wireless communication and radar systems.

关键词： optoelectronic tuning amplifier

Elemental Compositions of Clinopyroxenes from Southern Okinawa Trough Basalt:Implications for Magmatism and Structural Environment in an Initial Back-Arc Basin

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Journal of Ocean University of China 2024年第3期23卷 643-653页

作者： GUO kun ZHAI Shikui FAN di zhang Xia zhang Yu ZHU Zhimin Laoshan Laboratory Qingdao 266237China Key Laboratory of Submarine Geosciences and Prospecting Techniques Ministry of EducationCollege of Marine GeosciencesOcean University of ChinaQingdao 266100China Key Laboratory of Submarine Geosciences&Second Institute of Oceanography Ministry of Natural ResourcesHangzhou 310012China

The major and trace elemental compositions of clinopyroxene from basalt were used to characterize the nature of the primitive magma and structural environment beneath the southern Okinawa Trough(SOT),which is an initial back-arc basin at a continental *** clinopyroxenes in the basalt were augite with variable Mg^(#)contents(73.37-78.22).The regular variations in major oxide contents(i.e.,CaO,FeO,TiO_(2),and Cr)with decreasing Mg#implied that the clinopyroxenes evolved from being enriched in Mg,Ca,and Cr to being enriched in Fe and *** clinopyroxenes had relatively low rare earth element concentrations(7.51×10^(-6) to 12.68×10^(-6))and negative Eu anomalies(δEu=0.67-0.95).The Kd_(cpx) values of clinopyroxenes(0.2-0.26),which were used to examine whether the clinopyroxene was equilibrated with its host basalt,demonstrate that these clinopyroxene phenocrysts were not captured crystals but were instead produced by crystallization differentiation of the *** calculated clinopyroxene crystallization temperatures showed a narrow range of 990-1061℃,and their crystallization pressures ranged from 2.0 to 3.2 *** geochemistry features of these clinopyroxenes indicated that the parent magma belonged to the subalkaline tholeiitic magma series and suggested that the magma experienced crystallization differentiation of olivine,plagioclase,and clinopyroxene,where the crystallization of plagioclase occurred earlier than that of *** with geophysical data,this research on primitive magma and its crystallization differentiation from clinopyroxene indicates that the SOT is in the stage of‘seafloor spreading’and that basaltic rocks produced from tholeiitic magma represent the generation of oceanic crust.

关键词： trace elements clinopyroxenes southern Okinawa Trough seafloor spreading back-arc basin

Weight Analysis of Impact Factors of Interbedded Anti-Inclined Slopes Block-Flexure Toppling Based on Support Vector Regression

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Journal of Earth Science 2024年第2期35卷 568-582页

作者： Bocheng zhang huiming tang Yibing Ning kun Fang ding Xia Department of Engineering Geology and Geotechnical Engineering Faculty of EngineeringChina University of GeosciencesWuhan430074China Badong National Observation and Research Station of Geohazards China University of GeosciencesWuhan430074China College of Geological Engineering and Geomatics Chang’an UniversityXi’an710054China

Block-flexure toppling failure is frequently encountered in interbedded anti-inclined rock(IAR)slopes,and seriously threatens the construction of hydropower *** this study,we first investigated the Lean Reservoir area’s geological setting and the Linda landslide’s ***,uniform design and random design were used to design 110 training datasets and 31 testing datasets,***,the toppling response was obtained by using the discrete element ***,support vector regression was used to obtain the influence weights of 21 impact *** results show that the influence weight of the slope angle and rock formation dip angle on the toppling deformation among tertiary impact factors is 25.96%and 17.28%,respectively,which are much greater than the other 19 impact factors within the research *** the primary impact factors,the influence weight is sorted from large to small as slope geometry parameters,joints parameters,and rock mechanics *** parameters,especially the geometric parameters,cannot be ignored when evaluating the stability of IAR *** numerical simulation,it was qualitatively determined that failure surfaces of slopes were controlled by cross joints and that the rocks in the slope toe play a role in preventing slope deformation.

关键词： interbedded anti-inclined slopes block-flexure toppling impact factors numerical simulation support vector regression engineering geology

Bias distribution and regulation in photoelectrochemical overall water-splitting cells

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National Science Review 2024年第4期11卷 141-150页

作者： kun Dang Siqin Liu Lei wu Daojian tang Jing Xue Jiaming Wang Hongwei Ji Chuncheng Chen Yuchao zhang Jincai Zhao Key Laboratory of Photochemistry CAS ResearchEducation Center for Excellence in Molecular Sciences Institute of Chemistry Chinese Academy of Sciences University of Chinese Academy of Sciences

The water oxidation half-reaction at anodes is always considered the rate-limiting step of overall water splitting（OWS）,but the actual bias distribution between photoanodes and cathodes of photoelectro chemical（PEC） OWS cells has not been investigated *** this work,we find that,for PEC cells consisting of photoanodes（nickel-modified n-Si [Ni/n-Si] and α-Fe2O3） with low photovoltage(Vph 1V,the bias required for cathode activation can be significantly reduced,exhibiting a kinetics-controlled *** investigations show that the bias distribution can be regulated by tuning the electrolyte pH and using alternative half-reaction ***,a volcano plot is presented for the rational design of the overall reactions and unbiased PEC *** by this,an unbiased PEC cell consisting of a simple Ni/n-Si photoanode and Pt cathode is assembled,delivering a photo current density of 5.3±0.2 mA cm-2.

关键词： photoelectrochemistry overall reaction cell bias distribution photoanode water splitting

Multidomain Hybrid direct DG and Central difference Methods for Viscous Terms in Hyperbolic-Parabolic Equations

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Numerical Mathematics(Theory,Methods and Applications) 2024年第1期17卷 1-36页

作者： Weixiong Yuan Tiegang Liu bin zhang Kui Cao kun Wang LMIB and School of Mathematical Sciences Beihang UniversityBeijing 100191China

A class of multidomain hybrid methods of direct discontinuous Galerkin(DDG)methods and central difference(CD)schemes for the viscous terms is pro-posed in this *** conservative and nonconservative coupling modes are *** treat the shock wave,the nonconservative coupling mode automatically switch to conservative coupling mode to preserve the conservative property when discontinuities pass through the artiﬁcial *** maintain the accuracy of the hybrid methods,the Lagrange interpolation polynomials and their derivatives are reconstructed to handle the coupling cells in the DDG subdomain,while the values of ghost points for the CD subdomain are calculated by the approximate polynomials from the DDG *** linear stabilities of these methods are demonstrated in detail through von-Neumann *** multidomain hybrid DDG and CD meth-ods are then extended to one-and two-dimensional hyperbolic-parabolic *** results validate that the multidomain hybrid methods are high-order ac-curate in the smooth regions,robust for viscous shock simulations and capable to save computational cost.

关键词： direct discontinuous Galerkin central difference schemes multidomain hybrid methods viscous terms hyperbolic-parabolic equations

Single-atom Ni-N_(4) for enhanced electrochemical sensing

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Nano Research 2024年第8期17卷 7658-7664页

作者： Zhuhui Qin Bo tang Guiru zhang Chongqing Zhu kun Jiang Bowei zhang Fu-Zhen Xuan Shanghai Key Laboratory of Intelligent Sensing and Detection Technology East China University of Science and TechnologyShanghai 200237China Key Laboratory of Pressure Systems and Safety of Ministry of Education East China University of Science and TechnologyShanghai 200237China School of Mechanical and Power Engineering East China University of Science and TechnologyShanghai 200237China Key Laboratory of Theoretical and Computational Photochemistry Ministry of EducationCollege of ChemistryBeijing Normal UniversityBeijing 100875China Interdisciplinary Research Center School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China

Single-atom catalysts(SACs)attract widespread attention in heterogeneous catalysis due to their maximum atomic utilization efficiency and unique physical and chemical ***,their applications in chemical sensing keep huge potential but remain ***,a Ni-N_(4)-C SAC was synthesized for the trace detection of dopamine(DA)and uric acid(UA).The Ni-N_(4)-C SAC exhibited superior sensing performance compared to the Ni *** detection range for DA and UA were 0.05–75μM and 5–90μM with detection limits of 0.027 and 0.82μM,*** functional theory(DFT)computations indicate that Ni-N_(4)-C has a lower reaction barrier during electrochemical process,indicating that the atomic Ni sites possess higher intrinsic activity than Ni ***,DA and UA show strong potential dependency on the Ni-N_(4)-C catalyst,indicating its applicability for their concurrent *** work extends the application of SACs in chemical sensing.

关键词： single-atom catalysts chemical sensing dopamine uric acid