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Defence Technology（防务技术） 2024年第9期39卷 67-85页

作者： Shujun Zhang Xiaoting Rui Hailong Yu Xiaoli Dong Institute of Launch dynamics Nanjing University of Science and TechnologyNanjing 210094China National Key Laboratory of Complex Multibody System dynamics Nanjing 210094China

The launch dynamics theory for multibody systems emerges as an innovative and efficacious approach for the study of launch dynamics,capable of addressing the challenges of complex modeling,diminished computational efficiency,and imprecise analyses of system dynamic responses found in the dynamics research of intricate multi-rigid-flexible body systems,such as self-propelled *** advancement aims to enhance the firing accuracy and launch safety of self-propelled *** the shortfall of overlooking the band engraving process in existing theories,this study introduces a novel coupling calculation methodology for the launch dynamics of a self-propelled artillery multibody *** method leverages the ABAQUS subroutine interface VUAMP to compute the dynamic response of the projectile and barrel during the launch process of large-caliber self-propelled ***,it examines the changes in projectile resistance and band deformation in relation to projectile motion throughout the band engraving *** analysis of the computational outcomes with experimental data evidences that the proposed method offers a more precise depiction of the launch process of self-propelled artillery,thereby enhancing the accuracy of launch dynamics calculations for self-propelled artillery.

关键词： Self-propelled artillery Engraving process Multibody system dynamics Launch dynamics

Numerical simulation of the coupled dynamics model of the projectile engraving process

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International Journal of Mechanical System dynamics 2024年第2期4卷 188-201页

作者： Shujun Zhang Xiaoting Rui Hailong Yu Xiaoli Dong Institute of Launch dynamics Nanjing University of Science and TechnologyNanjingChina National Key Laboratory of Complex Multibody System dynamics NanjingChina

The projectile engraving process directly influences the projectile motion in-bore and impacts the firing accuracy,firing safety,and barrel life of the *** this reason,attention has been focused on this research *** address the limitations of the“instantaneous engraving”hypothesis adopted in the classical interior ballistic theory,the VUAMP user subroutine,one of ABAQUS's secondary development interfaces,is utilized in this paper to realize the modeling and numerical simulation of a coupled dynamics model of the projectile engraving *** addition to facilitating engineering applications,a polynomial fitting formula of the engraving resistance obtained by simulation is proposed and then used as a supplement to establish a closed and solvable interior ballistic model considering the projectile engraving *** comparing with test data,the simulation accuracy of the coupled dynamics model is *** results reveal that the engraving process takes 3.8 ms,accounting for 26%of the whole launch process,which takes 14.6 ms,demonstrating that the process is not *** results of this paper can serve as a reference for future studies on the coupled solution of the projectile engraving process and interior ballistics of guns or gun-like equipment.

关键词： projectile engraving process engraving resistance finite element method polynomial fitting interior ballistic simulation

Calculation of ship motions in steep waves with restoring and Froude-Krylov forces on an adaptive panel mesh with Gauss and analytic integration methods

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Journal of Hydrodynamics 2024年第2期36卷 275-289页

作者： Malwin Wermbter Moustafa Abdel-Maksoud Institute for Fluid dynamics and Ship Theory Hamburg University of TechnologyHamburgGermany

The impulse response method is a frequently used method to calculate ship seakeeping *** this paper,the restoring and Froude-Krylov calculation is conducted with constant evaluation of panel pressures as well as Gauss quadrature and an analytical *** applied panel grid is coarsened by an adaptive algorithm which is based on a normal vector *** comparison of methods is based on grid convergence studies which are followed by a verification of forces with computational fluid dynamics(CFD)results on the fixed duisburg test case in *** with experimental results in head,oblique and following waves show that all integration methods are *** exact integration is numerically sensitive in some *** quadrature is highly accurate;however,the additional effort is not beneficial since the geometrical accuracy has-stronger influence on the force amplitudes than the integration *** grid coarsening reduces the simulation time and is accurate up to a level,where the panel length comes close the *** added resistance at the investigated Froude number of 0.05 shows higher uncertainty levels,this applies to the results of both the numerical methods and model tests.

关键词： Ship hydrodynamics seakeeping impulse response method added resistance wave loads

Optimal impulsive rendezvous for highly elliptical orbits using linear primer vector theory

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Chinese Journal of Aeronautics 2024年第3期37卷 194-207页

作者： Maozhang ZHENG Jianjun LUO Zhaohui DANG National Key Laboratory of Aerospace Flight dynamics Northwestern Polytechnical UniversityXi’an 710072China

In this paper,minimum-fuel rendezvous is investigated for the case in which the reference orbit is highly *** this end,the well-known Tschauner-Hempel equations are used to describe the relative motions between rendezvous spacecraft and the ***’s primer vector theory is then applied on this linear but time-varying *** analytical solution of the required primer vector for this problem is then derived by using a recently developed *** the existing non-optimal solutions which don’t satisfy the conditions,the methods are further designed to improve the performance by shifting impulses or adding a new ***,two algorithms are developed for free-impulse time-fixed rendezvous *** first algorithm can determine the globally optimal trajectory with the optimal number of *** second one enables for fast trajectory *** proposed algorithms have been successfully applied to coplanar and three-dimensional rendezvous problems in which the target is flying on highly elliptical orbits.

关键词： Orbital transfer Optimal trajectory Primer vector Tschauner-Hempel equations Globally planning Fast planning

Earthquake potential across the North–South seismic belt of China

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Science Bulletin 2024年第2期69卷 179-182页

作者： Yanchuan Li Xinjian Shan Chunyan Qu Guohong Zhang Xiaogang Song State Key Laboratory of Earthquake dynamics Institute of GeologyChina Earthquake AdministrationBeijing 100029China

The elastic rebound theory,which frames our understanding of earthquakes,suggests that the accumulated elastic strain on faults will ultimately be released through earthquakes[1].As such,identifying the location,rate,and accumulation of slip deficit on faults constitutes a basis for seismic potential assessment[2].Interseismic coupling(ISC)refers to the ratio of the slip deficit rate on a fault to the far-field loading rate,where full and no coupling correspond to 100%and 0%slip deficits,respectively.

关键词： seismic belt fault

Unstable evolution of railway slope under the rainfall-vibration joint action

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Journal of Mountain Science 2024年第4期21卷 1419-1431页

作者： DONG Haoyu WANG Jiading ZHANG Dengfei LI Lin XU Yuanjun State Key Laboratory of Continental dynamics Department of GeologyNorthwest UniversityXi’an 710069China

Understanding the unstable evolution of railway slopes is the premise for preventing slope failure and ensuring the safe operation of ***,as two major factors affecting the stability of railway slopes,few scholars have explored the unstable evolution of railway slopes under the joint action of *** on the model test of sandy soil slope,the unstable evolution process of slope under locomotive vibration,rainfall,and rainfall-vibration joint action conditions was simulated in this *** comparing and analyzing the variation trends of soil pressure and water content of slope under these conditions,the change laws of pore pressure under the influence of vibration and rainfall were *** main control factors affecting the stability of slope structure under the joint action conditions were further *** with the slope failure phenomena under these three conditions,the causes of slope instability resulting from each leading factor were ***,according to the above conclusions,the unstable evolution of the slope under the rainfall-vibration joint action was *** test results show that the unstable evolution process of sandy soil slope,under the rainfall-vibration joint action,can be divided into:rainfall erosion cracking,vibration promotion penetrating,and slope instability sliding three *** the process of slope unstable evolution,rainfall and vibration play the roles of inducing and promoting slide *** addition,the deep cracks,which are the premise for the formation of the sliding surface,and the violent irregular fluctuation of soil pressure,which reflects the near penetration of the sliding surface,constitute the instability characteristics of the railway slope *** paper reveals the unstable evolution of sandy soil slopes under the joint action of rainfall-vibration,hoping to provide the theoretical basis for the early warning and prevention technology of railway slopes.

关键词： Rainfall vibration joint action Small scale model tests Unstable evolution process Unstable characteristics Inducing sliding and promoting sliding

Experimental and numerical investigation on alternatives to sandy gravel

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Defence Technology（防务技术） 2024年第1期31卷 130-141页

作者： V.Denefeld H.Aurich Fraunhofer Institute for High-Speed dynamics Ernst-Mach-Institut(EMI)Ernst-Zermelo-Str.479104FreiburgGermany Fraunhofer Institute for High-Speed dynamics Ernst-Mach-Institut(EMI)Am Christianswuhr 279400KandernGermany

The NATO agreement STANAG 4569 defines the protection levels for the occupants of logistic and light armored *** Allied Engineering Publication,AEP-55,Volume 2 document outlines the test conditions for underbelly improvised explosive device(IEDs),which must be buried in water-saturated sandy *** use of sandy gravel has some drawbacks,for instance reproducibility,time consumption,and *** paper focuses on the investigation of four alternatives to sandy gravel,which could produce similar specific and cumulative impulses:a concrete pot filled with water,a concrete pot filled with quartz sand,a steel pot without filling and a concrete pot filled with glass spheres(diameter 200μm—300μm)and different water *** impulses are measured with a ring technology developed at the Fraunhofer EMI.A numerical soil model based on the work of Marrs,2014 and Fi serov a,2006 and considering the soil moisture was used to simulate the experiments with glass spheres at different water contents,showing much better agreement with the experiments than the classical Laine&Sandvik model,even for high saturation *** results can be used to create new test conditions at original scale that are more cost-effective,more reproducible and simpler to manage in comparison to the current tests carried out with STANAG sandy gravel.

关键词： Improvised explosive device(IED) Specific impulse Momentum transfer Sandy gravel Glass spheres Numerical model Soil moisture

Tracing nitrate sources in one of the world's largest eutrophicated bays(Hangzhou Bay):insights from nitrogen and oxygen isotopes

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Acta Oceanologica Sinica 2024年第6期43卷 86-95页

作者： Zhi Yang Jianfang Chen Haiyan Jin Hongliang Li Zhongqiang Ji Yangjie Li Bin Wang Zhenyi Cao Qianna Chen Key Laboratory of Marine Ecosystem dynamics Second Institute of OceanographyMinistry of Natural ResourcesHangzhou 310012China State Key Laboratory of Satellite Ocean Environment dynamics Second Institute of OceanographyMinistry of Natural ResourcesHangzhou 310012China

Eutrophication caused by inputs of excess nitrogen(N) has become a serious environmental problem in Hangzhou Bay(China),but the sources of this nitrogen are not well *** this study,the August 2019 distributions of salinity,nutrients [nitrate(NO_(3)^(-)),nitrite,ammonium,and phosphate],and the stable isotopic composition of NO_(3)^(-)(δ^(15)N and δ^(18)O) were used to investigate sources of dissolved inorganic nitrogen(DIN) to Hangzhou B *** distributions of nitrate,salinity,and nitrate δ^(18)O indicate that the Qiantang River,the Changjiang River,and nearshore coastal waters may all contribute nitrate to the *** on the isotopic compositions of nitrate in these potential source waters and conservative mixing of nitrate in our study area,we suggest that the NO_(3)^(- )in Hangzhou B ay was likely derived mainly from soils,synthetic N fertilizer,and manure and ***-member modeling indicates that in the upper half of the bay,the Qiantang River was a very important DIN source,possibly contributing more than 50% of DIN in the bay head *** the lower half of the bay,DIN was sourced mainly from strongly intruding coastal *** coming directly from the Changjiang River made a relatively small contribution to Hangzhou Bay DIN in August 2019.

关键词： nitrogen isotopes oxygen isotopes nitrogen cycle nitrate sources Hangzhou Bay

Unknown system dynamics estimator-based impedance control for lower limb exoskeleton with enhanced performance

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Control Theory and Technology 2024年第1期22卷 56-68页

作者： Wenhao Zhang Peng Song Mingying Wu Qiang Li Xinmin Mo Pingxin Ji Northwest Institute of Mechanical and Electrical Engineering Xianyang712099ShaanxiChina Xi’an Exo-Smart dynamics Technology Ltd. Xi’an712046ShaanxiChina Department of Mechanical and Engineering Beijing Institute of TechnologyBeijing100081China

In this article, an unknown system dynamics estimator-based impedance control method is proposed for the lower limb exoskeleton to stimulate the tracking flexibility with the terminal target position when suffering parametric inaccuracies and unexpected disturbances. To reinforce the robust performance, via constructing the filtering operation-based dynamic relation, i.e., invariant manifold, the unknown system dynamics estimators are employed to maintain the accurate perturbation identification in both the hip and knee subsystem. Besides, a funnel control technique is designed to govern the convergence process within a minor overshoot and a higher steady-state precision. Meanwhile, an interactive complaint result can be obtained with the aid of the impedance control, where the prescribed terminal trajectory can be adjusted into the interaction variable-based target position by the force–position mapping, revealing the dynamic influence between the impedance coefficient (stiffness and damping) and the adjusted position magnitude. A sufficient stability analysis verifies the ultimately uniformly bounded results of all the error signals, and even the angle errors can be regulated within the predefined funnel boundary in the whole convergence. Finally, some simulations are provided to demonstrate the validity and superiority including the enhanced interaction flexibility and robustness.

关键词： Trajectory tracking Invariant manifold Funnel control Impedance control Lower limb exoskeleton

Impact of transparent exopolymer particles on the dynamics of dissolved organic carbon in the Amundsen Sea,Antarctica

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Advances in Polar Science 2024年第1期35卷 123-131页

作者： HU Ji XUE Siyou ZHAO Jun LI Dong ZHANG Haifeng YU Peisong ZHANG Cai YANG Xufeng PAN Jianming Key Laboratory of Marine Ecosystem dynamics Second Institute of OceanographyMinistry of Natural ResourcesHangzhou 310012China College of Ocean and Earth Sciences Xiamen UniversityXiamen 361102China

The Southern Ocean is an important carbon sink pool and plays a critical role in the global carbon *** Amundsen Sea was reported to be highly productive in inshore area in the Southern *** order to investigate the influence of transparent exopolymer particles(TEP)on the behavior of dissolved organic carbon(DOC)in this region,a comprehensive study was conducted,encompassing both open water areas and highly productive *** was found that microbial heterotrophic metabolism is the primary process responsible for the production of humic-like fluorescent components in the open *** relationship between apparent oxygen utilization and the two humic-like components can be accurately described by a power-law function,with a conversion rate consistent with that observed *** presence of TEP was found to have little impact on this ***,the study revealed the accumulation of DOC at the sea surface in the Amundsen Sea Polynya,suggesting that TEP may play a critical role in this *** findings contribute to a deeper understanding of the dynamics and surface accumulation of DOC in the Amundsen Sea Polynya,and provide valuable insights into the carbon cycle in this region.

关键词： dissolved organic matter chromophoric dissolved organic matter excitation-emission matrix coupled with parallel factor analysis transparent exopolymer particles Amundsen Sea Antarctica