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Data delivery delay and cross-layer packet size analysis for reliable transmission of Licklider transmission protocol in space networks

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Science China(Information Sciences) 2024年第9期67卷 229-244页

作者： Guannan YANG Ruhai WANG Kanglian ZHAO Wenfeng LI Dong YAN School of Information engineering Nanjing University of Finance and Economics Drayer department of Electrical and Computer engineering Lamar University School of Electronic Science and engineering Nanjing University Beijing aircraft Overall Design department

Delay/disruption tolerant networking(DTN) is proposed as a networking architecture to overcome challenging space communication characteristics for reliable data transmission service in presence of long propagation delays and/or lengthy link disruptions. Bundle protocol(BP) and Licklider Transmission Protocol(LTP) are the main key technologies for DTN. LTP red transmission offers a reliable transmission mechanism for space networks. One of the key metrics used to measure the performance of LTP in space applications is the end-to-end data delivery delay, which is influenced by factors such as the quality of spatial channels and the size of cross-layer packets. In this paper, an end-to-end reliable data delivery delay model of LTP red transmission is proposed using a roulette wheel algorithm, and the roulette wheel algorithm is more in line with the typical random characteristics in space networks. The proposed models are validated through real data transmission experiments on a semi-physical testing platform. Furthermore, the impact of cross-layer packet size on the performance of LTP reliable transmission is analyzed, with a focus on bundle size, block size, and segment size. The analysis and study results presented in this paper offer valuable contributions towards enhancing the reliability of LTP transmission in space communication scenarios.

关键词： Licklider transmission protocol DTN bundle protocol cross-layer packets size space communication

An effective nonlinear dynamic formulation to analyze grasping capability of soft pneumatic robotic gripper

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International Journal of Smart and Nano Materials 2024年第3期15卷 405-431页

作者： Qiping Xu Chenhang Ying Kehang Zhang Huiyu Xie Shiju E department of Robotics engineering Key Laboratory of Urban Rail Transit Intelligent Operation and Maintenance Technology&Equipment of Zhejiang ProvinceCollege of EngineeringZhejiang Normal UniversityJinhuaP.R.China

Soft pneumatic robotic grippers have found extensive applica-tions across various engineering domains,which prompts active research due to their splendid compliance,high flex-ibility,and safe human-robot interaction over conventional stiff *** simplified rod-based models prin-cipally focused on clarifying overall large deformation and bending postures of soft grippers from static or quasi-static perspectives,whereas it is challenging to elaborate grasping characteristics of soft grippers without considering contact interaction and nonlinear large deformation *** address this,based on absolute nodal coordinate formulation(ANCF),comprehensively allowing for structural complexity,geometric,material and boundary nonlinearities,and incorpor-ating Coulomb’friction law with a multiple-point contact method,we put forward an effective nonlinear dynamic mod-eling approach for exploring grasping capability of soft ***,we solved the established dynamic equations using Generalized-αscheme,and conducted thorough numer-ical simulation analysis on a three-jaw soft pneumatic gripper(SPG)in terms of grasping configurations,displacements and contact *** proposed dynamic approach can accurately both describe complicated deformed configurations along with stress distribution and provide a feasible solution to simulate grasping targets,whose effectiveness and precision were analyzed theoretically and verified experimentally,which may shed new light on devising and optimizing other multi-functional SPGs.

关键词： Nonlinear dynamic formulation soft pneumatic robotic grippers contact interaction grasping capability configuration variations

Time-dependent longitudinal responses of a shield tunnel induced by surcharge load:Theoretical prediction and analysis

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Underground Space 2024年第1期14卷 219-238页

作者： Fayun Liang Zhuwei Jiang Qiang Yuan Lin Li Rulu Wang department of Geotechnical engineering Tongji UniversityShanghai 200092China School of Highway Chang’an UniversityXi’an 710064China Shanghai Shentong Metro Group Limited maintenance Center Shanghai 20070China

The surcharge load at the ground surface inevitably breaks the original equilibrium state between the underneath tunnel and the surrounding soil,which will impact the service performance of a subway *** paper presents a novel semi-analytical approach for assessing the time-dependent,longitudinal responses of a subway tunnel in soft soil strata induced by the surcharge *** solution is developed based on the framework of the classical"two-stage method"but innovatively incorporates the effects of ground stratification,the consolidation process,and the longitudinal stiffness reduction of the ***’s poroelastic theory in conjunction with the Laplace-Fourier transform technique is selected to model the deformation of the stratified ground,while the Timoshenko beam on a Pasternak foundation is employed to model the mechanical responses of the *** proposed semi-analytical solution is validated not only by comparison with benchmark solutions and a finite element model,but also by predicting a well-documented field *** analyses are conducted to investigate the effects of the elastic modulus and the permeability coefficient of the stratified ground on the longitudinal responses of the *** is expected that the proposed solution can serve as a useful tool for evaluating the effects of the surcharge load on the longitudinal responses of a subway tunnel.

关键词： Time-dependent Longitudinal responses Stratified ground Subway tunnels Ground surface surcharge Consolidation

Evaluation and Influencing Factors on Particle Agglomeration in RAP

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Journal of Wuhan University of Technology(Materials Science) 2024年第1期39卷 60-68页

作者：唐伟李宁 ZHUANG Yuan ZHAN He YU Xin WU Wenxiu DING Gongying College of Civil and Transportation engineering Hohai UniversityNanjing 210098China Jiangsu Expressway engineering maintenance Technology Center Nanjing 211106China Jinhua Highway and Transportation Management Center Jinhua 321000China

Asphalt extraction test and scanning electron microscopy(SEM) were used for analysis of agglomerations of reclaimed asphalt pavement(RAP) particles. In order to quantify the agglomeration degree of RAP, the fineness modulus ratio(FMR) and the percentage loss index(PLI) were proposed. In addition, grey correlation analysis was conducted to discuss the relationship between particle agglomerations and RAP size,asphalt content(AC), and surface area. Two indexes indicate that the agglomeration degree increases in general as the RAP size reduces. This can be attributed to that particles are prone to agglomeration in the case of higher AC. Based on the SEM images and the material composition of RAP, the particle agglomeration in RAP can be classified into weak agglomeration and strong agglomeration. Grey correlation analysis shows that AC is the crucial factor affecting the agglomeration degree and RAP variability. In order to produce consistent and stable reclaimed mixtures, disposal measures of RAP are suggested to lower the AC of RAP.

关键词： RAP particle agglomeration grey correlation analysis asphalt content

Experimental investigation on the permeability of gap-graded soil due to horizontal suffusion considering boundary effect

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Journal of Rock Mechanics and Geotechnical engineering 2024年第3期16卷 1072-1084页

作者： Xuwei Wang Yeshuang Xu State Key Laboratory of Ocean engineering School of Naval ArchitectureOceanand Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China Shanghai Key Laboratory for Digital maintenance of Buildings and Infrastructure Department of Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China

The boundary condition is a crucial factor affecting the permeability variation due to *** experimental investigation on the permeability of gap-graded soil due to horizontal suffusion considering the boundary effect is conducted,where the hydraulic head difference(DH)varies,and the boundary includes non-loss and soil-loss *** samples are filled into seven soil storerooms connected in *** evaluation,the variation in content of fine sand(ΔR_(f))and the hydraulic conductivity of soils in each storeroom(C_(i))are *** the non-loss test,the soil sample filling area is divided into runoff,transited,and accumulated areas according to the negative or positive ΔR_(f) values.ΔR_(f) increases from negative to positive along the seepage path,and Ci decreases from runoff area to transited area and then rebounds in accumulated *** the soil-loss test,all soil sample filling areas belong to the runoff area,where the gentle-loss,strengthened-loss,and alleviated-loss parts are further divided.ΔR_(f) decreases from the gentle-loss part to the strengthened-loss part and then rebounds in the alleviated-loss part,and C_(i) increases and then decreases along the seepage *** relationship between ΔR_(f) and Ci is different with the boundary *** exponentially decreases with ΔR_(f) in the non-loss test and increases with ΔR_(f) generally in the soil-loss test.

关键词： Suffusion Permeability Experimental investigation Boundary effect Horizontal seepage

Comprehensive modeling strategy for thermomechanical tribological behavior analysis of railway vehicle disc brake system

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Friction 2024年第1期12卷 74-94页

作者： Jiabao YIN Chun LU Jiliang MO School of Mechanical engineering Southwest Jiaotong UniversityChengdu 610031China Technology and Equipment of Rail Transit Operation and maintenance Key Laboratory of Sichuan Province Chengdu 610031China

A comprehensive modeling strategy for studying the thermomechanical tribological behaviors is proposed in this *** wear degradation considering the influence of temperature(T)is predicted by Archard wear model with the help of the UMESHMOTION subroutine and arbitrary Lagrangian–Eulerian(ALE)remeshing *** the proposed method,the thermomechanical tribological behaviors of railway vehicle disc brake system composed of forged steel brake disc and Cu-based powder metallurgy(PM)friction block are studied *** effectiveness of the proposed methodology is validated by experimental test on a self-designed scaled brake test bench from the perspectives of interface temperature,wear degradation,friction noise and vibration,and contact status *** work can provide an effective way for the investigation of thermomechanical tribological behaviors in the engineering field.

关键词： tribological behaviors thermomechanical field wear prediction finite element simulation disc brake system railway vehicle

Pulses in ground motions identified through surface partial matching and their impact on seismic rocking consequence

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Earthquake engineering and engineering Vibration 2024年第1期23卷 35-50页

作者： Tang Yuchuan Wang Jiankang Wu Gang School of Civil engineering Southeast UniversityKey Laboratory of Concrete and Prestressed Concrete Structures of the Ministry of EducationNanjing 211102China National and Local Joint engineering Research Center for Intelligent Construction and maintenance Nanjing 211102China

In seismology and earthquake engineering,it is fundamental to identify and characterize the pulse-like features in pulse-type ground *** capture the pulses that dominate structural responses,this study establishes congruence and shift relationships between response spectrum surfaces.A similarity search between spectrum surfaces,supplemented with a similarity search in time series,has been applied to characterize the pulse-like features in pulse-type ground *** identified pulses are tested in predicting the rocking consequences of slender rectangular blocks under the original ground ***,the prediction is promising for the majority of the ground motions where the dominant pulse is correctly identified.

关键词： velocity pulse ground motion surface similarity rocking overturning

Study on creep deformation and energy development of underground surrounding rock under four‐dimensional support

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Deep Underground Science and engineering 2024年第1期3卷 25-38页

作者： Zhanguo Ma Junyu Sun Peng Gong Pengfei Yan Nan Cui Ruichong Zhang School of Mechanics and Civil engineering China University of Mining and TechnologyXuzhouChina State Key Laboratory of Intelligent Construction and Healthy Operation and maintenance of Deep Underground engineering China University of Mining and TechnologyXuzhouChina department of Mining engineering Colorado School of MinesGoldenUSA

There is an urgent need to develop optimal solutions for deformation control of deep high‐stress roadways,one of the critical problems in underground *** previously proposed four‐dimensional support(hereinafter 4D support),as a new support technology,can set the roadway surrounding rock under three‐dimensional pressure in the new balanced structure,and prevent instability of surrounding rock in underground ***,the influence of roadway depth and creep deformation on the surrounding rock supported by 4D support is still *** study investigated the influence of roadway depth and creep deformation time on the instability of surrounding rock by analyzing the energy *** elastic strain energy was analyzed using the program redeveloped in *** numerical simulation results indicate that the combined support mode of 4D roof supports and conventional side supports is highly applicable to the stability control of surrounding rock with a roadway depth exceeding 520 *** the increase of roadway depth,4D support can effectively restrain the area and depth of plastic deformation in the surrounding ***,4D support limits the accumulation range and rate of elastic strain energy as the creep deformation time increases.4D support can effectively reduce the plastic deformation of roadway surrounding rock and maintain the stability for a long deformation period of 6 *** confirmed by in situ monitoring results,4D support is more effective for the long‐term stability control of surrounding rock than conventional support.

关键词： coal mines elastic strain energy four‐dimensional support large roadway depth long‐term stability control plastic deformation surrounding rock

Knowledge and data jointly driven aeroengine gas path performance assessment method

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Chinese Journal of Aeronautics 2024年第5期37卷 533-557页

作者： Zhe WANG Xuyun FU Rui ZHANG Zhengfeng BAI Xiangzhao XIA Wei JIANG department of Mechanical engineering Harbin Institute of TechnologyWeihai 264209China Weihai Key Laboratory of Intelligent Operation and maintenance Harbin Institute of TechnologyWeihai 264209China Control System Design Laboratory AECC ShenYang Engine Research InstituteShenyang 110015China

Aeroengines,as the sole power source for aircraft,play a vital role in ensuring flight *** gas path,which represents the fundamental pathway for airflow within an aeroengine,directly impacts the aeroengine's performance,fuel efficiency,and ***,timely and accurate evaluation of gas path performance is of paramount *** paper proposes a knowledge and data jointly driven aeroengine gas path performance assessment method,combining Fingerprint and gas path parameter deviation ***,Fingerprint is used to correct gas path parameter deviation values,eliminating parameter shifts caused by non-component performance ***,coarse errors are removed using the Romanovsky criterion for short-term data divided by an equal-length overlapping sliding ***,an Ensemble Empirical Mode Decomposition and Non-Local Means(EEMD-NLM)filtering method is designed to“clean”data noise,completing the preprocessing for gas path parameter deviation ***,based on the characteristics of gas path parameter deviation values,a Dynamic Temporary Blended Network(DTBN)model is built to extract its temporal features,cascaded with Multi-Layer Perceptron(MLP),and combined with Fingerprint to construct a Dynamic Temporary Blended AutoEncoder(DTB-AutoEncoder).Eventually,by training this improved autoencoder,the aeroengine gas path multi-component performance assessment model is formed,which can sufficiently decouple the nonlinear mapping relationship between aeroengine gas path multi-component performance degradation and gas path parameter deviation values,thereby achieving the performance assessment of engine gas path *** practical application cases,the effectiveness of this model in assessing the aeroengine gas path multi-component performance is verified.

关键词： Performance assessment Aeroengine Fingerprint Gas path parameter deviation values Jointly drive