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Evolution of silicon particle damage on fatigue crack initiation and early propagation in an aluminum alloy

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Rare Metals 2023年第7期42卷 2470-2476页

作者： hang zhou Zheng Zhang School of Materials Science and Engineering Beihang UniversityBeijing100191China

Low-cycle fatigue tests under both mechanical cyclic and thermal cyclic loadings were conducted to study the behavior of fatigue crack initiation and early propagation by means of metallographic and scanning electron microscopy(SEM).The damage mode of silicon particles has significant influence on crack *** are induced from fractured particles in mechanical fatigue or from debonded particles in thermal *** of cracks by breaking through particles happens in particles with non-equiaxial particles,while initiation of cracks from debonded interfaces happens widely in clustered *** cracks induced by fracture particles,the subsequent coalescence of microcracks proceeds through the alternation of brittle fracture of *** sequent broken of particles takes the important part in the early propagation stage of fatigue crack.

关键词： Aluminum alloys Microstructure mechanism Crack initiation Silicon particles

Probing vector-like top partner from same-sign dilepton events at the LHC

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Communications in Theoretical Physics 2020年第10期72卷 80-86页

作者： hang zhou Ning Liu Physics Department and Institute of Theoretical Physics Nanjing Normal UniversityNanjing210023China

The standard model is a successful theory but is lacking a mechanism for neutrino mass generation as well as a solution to the naturalness *** the models that are proposed to simultaneously solve the two problems,heavy Majorana neutrinos and top partners are usually predicted to lead to a new decay mode of the top partner mediated by the heavy Majorana neutrinos:T→b W^+→b l^+l^+qq^*** this paper,we will study the observability of such a new signature via the pair production process of a top partner pp→TT→2 b+l^±l^±+4 j in a model independent *** performing Monte Carlo simulations,we present the 2σexclusion limits of the top partner mass and mixing parameters at the HL-LHC.

关键词： top quark partner LHC same sign leptons

Pressure-controlled elliptical cavity expansion under anisotropic initial stress: Elastic solution and its application

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Science China(Technological Sciences) 2016年第7期59卷 1100-1119页

作者： zhou hang KONG GangQiang LIU HanLong College of Civil Engineering Key Laboratory of New Technology for Construction of Cities in Mountain Area Chongqing University College of Civil and Transportation Engineering Key Laboratory of Ministry of Education for Geomechanics and Embankment EngineeringHohai University

This paper presents an elastic solution to the pressure-controlled elliptical cavity expansion problem under the anisotropic stress conditions. The problem is formulated by the assumption that an initial elliptical cavity is expanded under a uniform pressure and subjected to an in-plane initial horizontal pressure Kσ_0 and vertical pressure σ_0 at infinity. A conformal mapping technique is used to map the outer region of the initial elliptical cavity in the physical plane onto the inner region of a unit circle in the phase plane. Using the complex variable theory, the stress functions are derived; hence, the stress and displacement distributions around the elliptical cavity wall can be obtained. Furthermore, a closed-form solution to the pressure-expansion relationship is presented based on the elastic solution to the stress and displacement. Next, the proposed analytical solutions are validated by comparing with the Kirsch's solution and the finite element method(FEM). The solution to the presented pressure-controlled elliptical cavity expansion can be applied to two cases in practice. One is to employ the solution to the interpretation of the shear modulus of the soil or rocks and the in-situ stress in the pre-bored pressuremeter test under the lateral anisotropic initial stress condition. The other is the interpretation of the membrane expansion of a flat dilatometer test using the pressure-controlled elliptical cavity expansion solution. The two cases in practice confirm the usefulness of the present analytical solution.

关键词： elasticity pressure-controlled elliptical cavity expansion stress displacement pressuremeter test flat dilatometer test

Generalized Minimum Rank Distance of Variable-Rate Linear Network Error Correction Codes

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Wuhan University Journal of Natural Sciences 2021年第1期26卷 19-23页

作者： zhou hang School of Economics Northwest University of Political Science and LawXi’an 710122ShaanxiChina

By extending the notion of the minimum distance for linear network error correction code(LNEC), this paper introduces the concept of generalized minimum rank distance(GMRD) of variable-rate linear network error correction codes. The basic properties of GMRD are investigated. It is proved that GMRD can characterize the error correction/detection capability of variable-rate linear network error correction codes when the source transmits the messages at several different rates.

关键词： network error correction code error pattern generalized minimum distance variable-rate

Design of integral sliding mode guidance law based on disturbance observer

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Journal of Systems Engineering and Electronics 2024年第1期35卷 186-194页

作者： zhou Jianping Zhang Wenjie zhou hang LI Qiang XIA Qunli School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China School of Informatic Engineering Mianyang Techers’CollegeMianyang 62100China Beijing Institute of Electronic System Engineering Beijing 100854China Beijing Institute of Space Long March Vehicle Beijing 100076China

With the increasing precision of guidance,the impact of autopilot dynamic characteristics and target maneuvering abilities on precision guidance is becoming more and more *** order to reduce or even eliminate the autopilot dynamic operation and the target maneuvering influence,this paper suggests a guidance system model involving a novel integral sliding mode guidance law(ISMGL).The method utilizes the dynamic characteristics and the impact angle,combined with a sliding mode surface scheme that includes the desired line-ofsight angle,line-of-sight angular rate,and second-order differential of the angular *** the same time,the evaluation scenario considere the target maneuvering in the system as the external disturbance,and the non-homogeneous disturbance observer estimate the target maneuvering as a compensation of the guidance *** proposed system’s stability is proven based on the Lyapunov stability *** simulations reveale that ISMGL effectively intercepted large maneuvering targets and present a smaller miss-distance compared with traditional linear sliding mode guidance laws and trajectory shaping guidance ***,ISMGL has a more accurate impact angle and fast convergence speed.

关键词： disturbance observer pilot dynamics integral sliding mode impact angle constraint maneuvering target

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不同冷却方式下高温混凝土的动态力学特性

爆炸与冲击 2025年第1期45卷 1-15页

作者：吴栩霆王振周航张国凯李硕标南京理工大学机械工程学院江苏南京210094

为了研究高温混凝土在不同冷却方式下的动态力学特性,通过φ74 mm大口径分离式霍普金森压杆对不同冷却方式处理下不同温度的C30圆柱形混凝土试样进行了动态力学性能试验,得到了其在热、水、力联合作用下的力学特性,探究了冷却方式、温... 详细信息

为了研究高温混凝土在不同冷却方式下的动态力学特性,通过φ74 mm大口径分离式霍普金森压杆对不同冷却方式处理下不同温度的C30圆柱形混凝土试样进行了动态力学性能试验,得到了其在热、水、力联合作用下的力学特性,探究了冷却方式、温度和加载条件对平均应变率的影响,重点分析了高温混凝土在不同方式冷却后的动态应力-应变曲线,以及冷却方式、温度和加载速率对其破碎形态、动态抗压强度、弹性模量、峰值应变及一系列动态效应的影响。结果表明:水冷混凝土试样的平均应变率受温度的影响更明显,不同冷却方式下加载速度与平均应变率近似呈线性关系;当温度达到400℃及以上时,试样颜色发生明显改变,相同温度下,水冷试样比自然冷却试样的颜色更深,出现更多细微裂纹,骨料形态破坏更严重;不同冷却方式下混凝土的动态抗压强度均与加载速度成正比,与加热温度成反比;水冷混凝土试样的弹性模量损伤系数低于自然冷却试样;高温混凝土试样的峰值应变与加热温度成正比,与加载速度成反比,且水冷混凝土试样的峰值应变相对值要高于自然冷却试样;混凝土的动载荷增加因子与温度及加载速度均成正比,且温度越高,混凝土的应变率效应越明显;当温度在200℃时,混凝土耗能系数出现反弹现象。

关键词：冷却方式冲击高温混凝土分离式霍普金森压杆动态力学特性破坏形态

Development of underwater electric manipulator based on interventional autonomous underwater vehicle (AUV)

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第3期25卷 238-250页

作者： Xiaohui HU Jiawang CHEN hang zhou Ziqiang REN Ocean cllege Zhejiang UniversityZhoushan 316021China Hainan Institute Zhejiang UniversitySanya 572025China The Engineering Research Center of Oceanic Sensing Technology and Equipment Ministry of EducationZhoushan 316021China

In applications such as marine rescue,marine science,archaeology,and offshore industries,autonomous underwater vehicles(AUVs)are frequently used for survey missions and monitoring tasks,with most operations being performed by manned submersibles or remotely operated vehicles(ROVs)equipped with robotic arms,as they can be operated remotely for days without ***,they require expensive marine vessels and specialist pilots to operate *** exploring oceans are no longer satisfied with the use of manned submersibles and *** is a growing desire for seabed exploration to be performed using smarter,more flexible,and automated *** improving the field operation and intervention capability of AUVs,large-scale and long-range seafloor exploration and sampling can be performed without the support of a mother ship,making it a more effective,economical,convenient,and rapid means of seafloor exploration and sampling operations,and playing a critical role in marine resource *** this study,we explored the integration technology of underwater electric robotic arms and AUVs and designed a new set of electric manipulators suitable for water depths greater than 500 *** reliability of the key components was analyzed by finite element analysis and,based on the theory of robot kinematics and dynamics,simulations were performed to verify the reliability of the key *** were conducted on land and underwater,trajectory tracking experiments were completed,and the experimental data in air and water were compared and ***,the objectives for further research on the autonomous control of the manipulator underwater were proposed.

关键词： Underwater electric manipulator Inverse kinematics Trajectory planning Trajectory tracking accuracy

Large spin Hall effect and tunneling magnetoresistance in iridium-based magnetic tunnel junctions

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Science China(Physics,Mechanics & Astronomy) 2020年第1期63卷 86-92页

作者： JiaQi zhou hang Yu zhou Arnaud Boumel WeiSheng Zhaop Fert Beijing Institute BDBCSchool of MicroelectronicsBeihang UniversityBeijing 100191China Centre de Nanosciences et de Nanotechnologies CNRSUniversite Paris-SudUniversite Paris-SaclayPalaiseau 91120France

Magnetic tunnel junctions(MTJs)switched by spin-orbit torque(SOT)have attracted substantial interest owing to their advantages of ultrahigh speed and prolonged *** field-free magnetization switching and high tunneling magnetoresistance(TMR)are critical for the practical application of SOT magnetic random access memory(MRAM).In this work,we propose an MTJ structure based on an iridium(Ir)bottom *** metal is a desirable candidate for field-free SOT switching owing to its strong intrinsic spin Hall conductivity(SHC),which can be enhanced via ***,we study TMR in Ir-based MTJs with symmetric and asymmetric ***-based MTJs exhibit large TMR,which can be further enhanced by heavy metal symmetry owing to the resonant tunneling *** comprehensive investigations illustrate that Ir-based MTJs are promising candidates for realizing SOT switching and high TMR.

关键词： magnetic tunnel junction spin Hall effect tunneling magnetoresistance

Influence of stress anisotropy on the cylindrical cavity expansion in undrained elastic-perfectly plastic soil

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Science China(Technological Sciences) 2018年第3期61卷 370-380页

作者： zhou hang LIU HanLong ZHA YaHui YIN Feng Key Laboratory of New Technology for Construction of Cities in Mountain Area School of Civil Engineering Chongqing University State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining and Technology

This work presents an analysis of the influence of stress anisotropy on cylindrical cavity expansions in an undrained elastic-perfectly plastic soil. This problem was formulated by assuming a large strain in both the elastic and plastic zones around the cavity and a plain strain condition during the cavity expansion process. The solutions for the limit pressure, stress, and excess pore pressure were obtained by introducing the anisotropic initial stress coefficient K_0 into the conventional cylindrical cavity expansion *** proposed solutions were then used to interpret the piezocone penetration test, and the suitability of the solutions was verified by comparing the prediction with the piezocone penetration test data. Subsequently, parametric studies were carried out to investigate the influence of stress anisotropy on the stress, excess pores pressure distributions around an expanding cylindrical cavity, and limit pressure. The results show that the proposed cylindrical cavity expansion method under stress anisotropy is suitable and can be used to investigate the piezocone cone test. The present work improves upon the conventional theoretical framework of cavity expansion and can be applied to the determination of the stresses around axially loaded piles and around in-situ testing devices such as penetrometers.

关键词： anisotropy cylindrical cavity expansion undrained elastic-perfectly plastic