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A review on DFACS(II):Modeling and analysis of disturbances and noises

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Chinese Journal of Aeronautics 2024年第5期37卷 120-147页

作者： Chenglei YUE Bohan JIAO Zhaohui DANG Xiaokui YUE Yonghe ZHANG Yuanqing XIA Li DUAN Qinglei HU Qifan LIU Pengcheng WANG Ming GUO Zhansheng DUAN Bing CUI Chu ZHANG Xiaodong SHAO school of Astronautics Northwestern Polytechnical UniversityXi’an 710072China Innovation Academy for Microsatellites Chinese Academy of SciencesShanghai 710699China school of automation Beijing Institute of TechnologyBeijing 100081China Institute of mechanics Chinese Academy of SciencesBeijing 710043China school of automation Science and Electrical engineering Beihang UniversityBeijing 100191China school of automation Science and engineering Xi’an Jiaotong UniversityXi’an 710049China

This paper presents Part II of a review on DFACS,which specifically focuses on the modeling and analysis of disturbances and noises in *** Part I,the system composition and dynamics model of the DFACS were *** this paper,we discuss the effects of disturbance forces and noises on the system,and summarize various analysis and modeling methods for these interferences,including the integral method,frequency domain analysis method,and magnitude evaluation *** analyzing the impact of disturbances and noises on the system,the paper also summarizes the system’s performance under slight ***,we highlight current research difficulties in the field of DFACS noise ***,this paper provides valuable insights into the modeling and analysis of disturbances and noises in DFACSs,and identifies key areas for future research.

关键词： Drag-free DFACS Disturbance Analysis Noise Analysis Frequency Domain Analysis Performance Evaluation

A review on DFACS(I):System design and dynamics modeling

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Chinese Journal of Aeronautics 2024年第5期37卷 92-119页

作者： Bohan JIAO Qifan LIU Zhaohui DANG Xiaokui YUE Yonghe ZHANG Yuanqing XIA Li DUAN Qinglei HU Chenglei YUE Pengcheng WANG Ming GUO Zhansheng DUAN Bing CUI Chu ZHANG Xiaodong SHAO school of Astronautics Northwestern Polytechnical UniversityXi’an 710072China Innovation Academy for Microsatellites Chinese Academy of SciencesShanghai 710699China school of automation Beijing Institute of TechnologyBeijing 100081China Institute of mechanics Chinese Academy of SciencesBeijing 710043China school of automation Science and Electrical engineering Beihang UniversityBeijing 100191China school of automation Science and engineering Xi’an Jiaotong UniversityXi’an 710049China

The Drag-Free and Attitude Control System(DFACS)is a critical platform for various space missions,including high precision satellite navigation,geoscience and gravity field measurement,and space scientific *** paper presents a comprehensive review of over sixty years of research on the design and dynamics model of ***,we examine the open literature on DFACS and its applications in Drag-Free missions,providing readers with necessary background information on the ***,we analyze the system configurations and main characteristics of different DFACSs,paying particular attention to the coupling mechanism between the system configuration and dynamics ***,we summarize the dynamics modeling methods and main dynamics models of DFACS from multiple perspectives,including common fundamentals and specific ***,we identify current challenges and technological difficulties in the system design and dynamics modeling of DFACS,while suggesting potential avenues for future *** paper aims to provide readers with a comprehensive understanding of the state-of-the-art in DFACS research,as well as the future prospects and challenges in this field.

关键词： Drag-Free DFACS System Design Dynamics Modeling Control design

Granular collapse in fluids:Dynamics and flow regime identification

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颗粒学报（英文版） 2024年第9期92卷 30-41页

作者： Hu Tang Bisong Lin Dengming Wang Department of mechanics and engineering Science School of Civil Engineering and MechanicsKey Laboratory of Mechanics on Disaster and Environment in Western China of Ministry of EducationLanzhou UniversityLanzhou730000China

The collapse of granular material in fluids is a prevalent phenomenon in both natural and industrial processes,displaying a notable sensitivity to initial configuration of the *** study is specifically oriented towards falling process of collapsing material under various fluid conditions,employing the computational fluid dynamics-discrete element method(CFD-DEM)to primarily investigate the dy-namics and scaling laws of deposit morphology of collapsed *** a comprehensive analysis of particle sedimentation in fluids,we introduce a refined inertial characteristic time for granular collapse within the inertial ***,we propose modifications to conventional fluid-particle density ratio and Reynolds number,aiming to enhance the accuracy of depicting collapse dy-namics and identifying flow regimes across diverse column heights and fluid ***,we construct a phase diagram of flow regimes using modified dimensionless numbers,emphasizing the role of column height in transition between viscous and inertial *** parameters demonstrate enhanced relevance in governing the collapse of immersed granular columns,thereby contributing to a more nuanced understanding of fluid-particle interations in dense granular flows under different regimes.

关键词： Collapse Computational fluid dynamics-discrete element method Dynamic Flow regime Immersed granular material

New Insight into the Flexoelectricity in the View of mechanics of Materials:Prismatic Beams Subjected to Bending

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Acta Mechanica Solida Sinica 2024年第4期37卷 555-569页

作者： Xu Yang Lingling Chen Shengyou Yang Department of engineering mechanics School of Civil EngineeringShandong UniversityJinan250061China

Flexoelectricity is a fascinating electromechanical phenomenon that occurs in non-homogeneously deformed dielectric *** piezoelectricity,the flexoelectric effect is highly dependent on both the material scale and the deformation *** several theoretical models have been proposed to explain the mechanism of flexoelectricity,these models can be rather complicated for those who are interested in studying the *** paper aims to simplify the understanding of flexoelectricity by focusing on the bending behavior of a prismatic dielectric beam from a mechanics of material *** avoid using complicated mathematical formulations based on continuum mechanics,including advanced tensor algebra and calculus of *** formulation clearly explains how inhomogeneous deformations and material size affect the electromechanical coupling,changing the effective bending stiffness,deflection,and rotation angles of a bending *** hope this paper can help undergraduate students and researchers,who are unfamiliar with the electromechanical coupling in flexoelectricity,to develop an understanding of this phenomenon and encourage further research in this area.

关键词： bending formulation dielectric

Numerical investigation on compressible flow around a cylinder in proximity to the heated wall

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Journal of Hydrodynamics 2024年第3期36卷 519-533页

作者： Yu-lu Liu Jun-wang Qu Yi-zhou Tao Yong-guang Lyu Xiang Qiu Shanghai Institute of Technology School of ScienceShanghai201418China Shanghai Key Laboratory of mechanics in Energy engineering Shanghai Institute of Applied Mathematics and MechanicsSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai200072China

In this study,direct numerical simulations were conducted to investigate the compressible flow around a circular cylinder near a heated wall at a Reynolds number(Re)of 500 and a Mach number(Ma)of *** heating ratio T^(*)ranging from 1.0 to 1.6 represents the different situations of a heated wall,whereas the gap ratio ranges from 0.3 to *** study analyzed the impact of heating effect and wall proximity on flow characteristics and aerodynamic *** results indicated that the stability of the flow was enhanced as the gap ratio decreased or the heating ratio *** the calculation of enstrophy,it was found that the strength of shedding vortices weakens with a decrease in gap ratio or an increase in heating ***,the mean drag coefficient decreases as the heating ratio increases or the gap ratio *** contrast,the mean lift coefficient initially decreases and then increases as the gap ratio ***,the drag reduction mechanism was analyzed by examining the pressure distribution on the surface of the cylinder.

关键词： Compressible flow wall proximity heating effect stability enstrophy

Strong shock propagation for the finite-source circular blast in a confined domain

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Applied Mathematics and mechanics(English Edition) 2024年第6期45卷 1071-1084页

作者： Qihang MA Kaileong CHONG Bofu WANG Quan ZHOU Shanghai Key Laboratory of mechanics in Energy engineering Shanghai Institute of Applied Mathematics and MechanicsSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai 200072China Shanghai Institute of Aircraft mechanics and Control Shanghai 200092China

The circular explosion wave produced by the abrupt discharge of gas from a high-temperature heat source serves as a crucial model for addressing explosion phenomena in compressible *** reflection of the primary shock and its propagation within a confined domain are studied both theoretically and numerically in this *** the assumption of strong shock,the scaling law governing propagation of the main shock is *** dimensionless frequency of reflected shock propagation is associated with the confined *** numerical simulation for the circular explosion problem in a confined domain is performed for *** the influence of confinement,the principal shock wave systematically undergoes reflection within the domain until it weakens,leading to the non-monotonic attenuation of kinetic energy in the explosion fireball and periodic oscillations of the fireball volume with a certain *** simulation results indicate that the frequency of kinetic energy attenuation and the volume oscillation of the explosive fireball align consistently with the scaling law.

关键词： explosion confinement main shock frequency

Experimental study of the damage characteristics of rocks containing non-penetrating cracks under cyclic loading

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International Journal of Mining Science and Technology 2024年第2期34卷 197-210页

作者： Jun Xu Xiaochun Xiao Lu Ma Sen Luo Jiaxu Jin Baijian Wu school of mechanics and engineering Liaoning Technical UniversityFuxin 123000China school of Civil engineering Liaoning Technical UniversityFuxin 123000China Department of engineering mechanics Southeast UniversityNanjing 211189China

The damage evolution process of non-penetrating cracks often causes some unexpected engineering *** specimens containing non-penetrating crack(s)are used to study the damage evolution and characteristics under cyclic *** results show that under cyclic loading,the relationship between the number of non-penetrating crack(s)and the characteristic parameters(cyclic number,peak stress,peak strain,failure stress,and failure strain)of the pre-cracked specimens can be represented by a decreasing linear *** damage evolution equation is fitted by calibrating the accumulative plastic strain for each cycle,and the damage constitutive equation is proposed by the concept of effective ***,non-penetrating cracks are more likely to cause uneven stress distribution,damage accumulation,and local failure of *** local failure can change the stress distribution and relieve the inhibition of non-penetrating crack extension and eventually cause a dramatic destruction of the ***,the evolution process caused by non-penetrating cracks can be regarded as one of the important reasons for inducing *** results are expected to improve the understanding of the process of spalling formation and rockburst and can be used to analyze the stability of rocks or rock structures.

关键词： Damage characteristics Constitutive model Fissured rocks Non-penetrating crack Cyclic loading

Interface property of dissimilar Ti-6Al-4V/AA1050 composite laminate made by non-equal channel lateral co-extrusion and heat treatment

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Defence Technology（防务技术） 2024年第3期33卷 197-208页

作者： Juan Liao Mengmeng Tian Xin Xue school of Mechanical engineering and automation Fuzhou UniversityFuzhou 350116China

The purpose of this paper is to examine the effect of processing parameters and subsequent heat treatments on the microstructures and bonding strengths of Ti-6Al-4V/AA1050 laminations formed via a non-equal channel lateral co-extrusion *** microstructural evolution and growth mechanism in the diffusion layer were discussed further to optimize the bonding quality by appropriately adjusting process *** electron microscopes(SEM),energy dispersive spectrometer(EDS),and X-ray diffraction(XRD)were used to characterize interfacial diffusion *** shear test was used to determine the mechanical properties of the interfacial diffusion *** experimental results indicate that it is possible to co-extrusion Ti-6Al-4V/AA1050 compound profiles using non-equal channel lateral *** heat treatment processes affect the thickness of the diffusion *** the temperature and time of heat treatment increase,the thickness of the reaction layers increases ***,the shear strength of the Ti-6Al-4V/AA1050 composite interface is proportional to the diffusion layer *** is observed that a medium interface thickness results in superior mechanical performance when compared to neither a greater nor a lesser interface *** characterization of all heat treatments reveals that the only intermetallic compound observed in the diffusion layers is TiAl_(3).Due to the inter-diffusion of Ti and Al atoms,the TiAl_(3) layer grows primarily at AA1050/TiAl_(3) interfaces.

关键词： Shear strength Co-extrusion Heat treatment Microstructure Intermetallic compounds

Dynamic thermal rating assessment of oil-immersed power transformers for multiple operating conditions

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High Voltage 2024年第1期9卷 195-205页

作者： Chen Zhang Xuzhu Dong Jiangjun Ruan Yongqing Deng school of Electrical engineering and automation Wuhan UniversityWuhanHubeiChina

In this article,the dynamic thermal rating assessment method of oil-immersed power transformer with multiple operating conditions is proposed,considering the constraints of hot spot temperature(HST),top oil temperature,losses of life and the maximum allowable current of on-load tap changer(OLTC)or bushing,which can determine the dynamic load curves under different operating conditions and give the most sensitive constraints to limit the dynamic load *** improve the accuracy of HST estimation,the temperature estimation model is also improved and the thermal parameters are optimised using the HST measured by optical ***,several application examples are studied for transformers in different *** results show that the normal cyclic dynamic transformer rating(DTR)is mainly limited by the losses of life when the ambient temperature is high,and the average load factor can be increased to 0.82 with a maximum load capacity of *** main limiting factor of short-term DTR is the OLTC or bushing current constraint,and the average load factor can be increased to *** maximum load capacity of the transformer under both operating conditions is 23%and 50%higher than its rated load capacity,indicating that the transformer still has a large load potential available.

关键词： load thermal power