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Laboratory investigation on mechanisms of stress wave propagations in porous media

Science China(Technological Sciences) 2009年第5期52卷 1374-1389页

作者： JU Yang YANG YongMing MAO YanZhe LIU HongBin WANG HuiJie State Key Laboratory of Coal Resources and Safe Mining China University of Mining&TechnologyBeijing 100083China Department of Mechanical and manufacturing engineering The University of Calgary2500 University Drive NW CalgaryAB T2N 1N4Canada University of Illinois at Urbana-Champaign 1110 West Green StreetUrbanaIL 61801USA Beijing Tongchen design of Architecture Ltd Beijing 100044China

A number of porous models having the similar statistical characteristics of pores and physical properties with natural sandstones have been produced using reactive powder concrete(RPC) and ***-Hopkinson-Pressure-Bar tests and CT scans have been carried out on the models with the various porosities to probe the performance of wave propagations and the responses of pores and the matrix during wave *** is shown that porosities significantly influence wave *** an identical impact strain rate,the greater the porosity is,the larger the amplitude of the reflected wave appears,the more the peak in the reflected wave presents,and the smaller the amplitude of the trans-mitted wave turns out.A single peak emerges in the reflected wave when the porosity falls down to 5%.The larger the impact strain rate,the much remarkable the *** energy-dissipated ratio of porous models,i.e.,WJ /WI,linearly increases with the increment of *** ratio is sensitive to the impact strain *** in the performance of wave propagations and energy dissipation result from the varied mechanisms that pores response to *** the porosity less than 10%,the mechanism appears to be a process fracturing the matrix to generate new surfaces or *** has primarily been dissipated in creating new surfaces or *** apparent pore deformation takes *** impact strain rate takes little effect on pore *** the porosity of 15% or more,the mechanism works depending on the impact strain *** a low impact strain rate applies,the mechanism still appears to crack the matrix to generate surfaces or pores,but the amount is lower as compared to the case with a low *** a large impact stain rate applies,the mechanism combines both fracturing the matrix and deforming the pores,with the deforming pores *** vast majority of energy has been dissipated to deform *** high porosity and impact strain rate c

关键词： stress wave porous media propagation mechanism sandstones pores CT scan

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Development of a Side Door Composite Impact Beam for the Automotive Industry

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Open Journal of Composite Materials 2024年第1期14卷 1-14页

作者： Vinay Papaiya Jens Schuster Yousuf Pasha Shaik Department of Applied Logistics and Polymer Sciences University of Applied Sciences Kaiserslautern Institute for Plastics and Engineering West Pfalz (IKW) Pirmasens Germany

The automobile industry has been searching for vehicles that use less energy and emit fewer pollutants, which has resulted in a high demand for fuel-efficient vehicles. Because of their higher strength-to-weight ratio compared to traditional steel, using fiber-reinforcement composite materials in automobile bodies has emerged as the most effective strategy for improving fuel efficiency while maintaining safety standards. This research paper examined the utilization of fiber-reinforced composite materials in car bodies to meet the increasing consumer demand for fuel-efficient and eco-friendly vehicles. It particularly focused on a carbon-aramid fiber-reinforced composite impact beam for passenger car side door impact protection. Despite the encouraging prospects of the carbon-aramid fiber-reinforced beam, the research uncovered substantial defects in the fabrication process, resulting in diminished load-bearing capacity and energy absorption. As a result, the beam was un-successful in three-point bending tests. This was accomplished by using an I cross-section design with varying thickness because of the higher area moment of inertia. Vacuum-assisted resin transfer molding (VARTM) manufacturing process was used and the finished beam underwent to three-point bending tests.

关键词： Side-Door Impact Beam Impact Energy Absorption Carbon-Aramid Reinforcement VARTM

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Numerical Simulation of Focused Wave and Its Uncertainty Analysis

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Journal of Shanghai Jiaotong university(Science) 2018年第4期23卷 475-481页

作者： BAI Junli MA Ning GU Xieehong State Key Laboratory of Ocean Engineerin Collaborative Innovation center for advanced Ship and Deep-Sea Exploration Shanghai Jiao Tong UniversityShanghai 200240China

On the basis of the transient water wave(TWW) theory,focused wave is generated in the circulating water *** simulation of the focused wave is carried out by solving the Reynolds averaged NavierStokes(RANS) *** dynamic grid technique is adopted to simulate the motion of the wave maker,and the volume of fluid(VOF) method is used to capture the free surface of the *** simulation results are compared with the measured data,and good agreement is *** quantitative estimation of the numerical simulation error and uncertainty,the uncertainty analysis method recommended by the International Towing Tank Conference(ITTC) procedure is performed for the simulation results of the surface elevations at different *** grid-convergence and time-step-size convergence studies are conducted using three types of grids and time step *** simulation results are all monotonously convergent in the verification procedure,and the validations of the simulated surface elevations with the positions at 3.5,4.0 and 4.5 m are all achieved by comparing with the validation *** is found that the numerical simulation errors caused by the grid and time-step-size in the convergence studies have the same order of *** addition,the numerical errors and uncertainties for the surface elevations at different positions are compared and discussed in *** paper presents the first attempt to carry out the uncertainty analysis of the simulation of focused wave,and the effectiveness of the proposed verification and validation procedures in the uncertainty analysis is demonstrated.

关键词： focused wave uncertainty analysis verification validation Reynolds averaged Navier-Stokes(RANS) equations

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Advantage of selective production of green rusts for Sb(Ⅴ) removal in Fe(0) electrocoagulation

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Chinese Chemical Letters 2020年第10期31卷 2779-2783页

作者： Di Cao Meng Qiao Angzhen Li Jingwei Hao Xu Zhao Key Laboratory of Drinking Water Science and Technology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China University of Chinese Academy of Sciences Beijing 100049China China ENFI engineering Corporation Beijing 100038China China Academy of Urban Planning and design Beijing 100037China

The re moval efficiency of pollutants in Fe(O) electrocoagulation(EC) has been associated closely with the speciation of generated Fe(Ⅱ)/Fe(Ⅲ) oxides during this process,which is very complicated and can be affected by various *** this work,in-situ Raman,X-ray diffraction and some other techniques have been used to study the speciation of Fe under different conditions and to establish a relationship between Fe speciation and Sb(V) removal *** indicated that concentration of dissolved oxygen(DO)is a key factor influencing Fe(O) *** was found that green rusts(GRs) were formed and were then transformed into magnetite at lower DO concentration,and Sb(V) removal efficiency reached 99.9% after30 min of *** contrast,γ-FeOOH was formed at high DO concentration,and the removal efficiency of Sb(V) after 30 min of EC was only 72.8%.In the presence of sulfite and phosphate with low concentrations,GRs can be stabilized and benefit the removal of Sb(V).We believe this work will provide some new insights on the mechanism of Fe(O) EC and the effective removal of other pollutants during Fe(O)EC process.

关键词： Iron electrocoagulation Antimony Green rusts Sodium sulfite Phosphate

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High-throughput microfabrication of axially tunable helices

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Photonics Research 2022年第2期10卷 303-315页

作者： He Cheng Pooria Golvari Chun Xia Mingman Sun Meng Zhang Stephen M.Kuebler Xiaoming Yu CREOL The College of Optics and PhotonicsUniversity of Central FloridaOrlandoFlorida 32816USA Department of Chemistry University of Central FloridaOrlandoFlorida 32816USA Department of Industrial and manufacturing Systems engineering Kansas State UniversityManhattanKansas 66506USA Department of Material Science and engineering University of Central FloridaOrlandoFlorida 32816USA

Helical structures exhibit novel optical and mechanical properties and are commonly used in different fields such as metamaterials and microfluidics. A few methods exist for fabricating helical microstructures, but none of them has the throughput or flexibility required for patterning a large surface area with tunable pitch. In this paper, we report a method for fabricating helical structures with adjustable forms over large areas based on multiphoton polymerization(MPP) using single-exposure, three dimensionally structured, self-accelerating, axially tunable light fields. The light fields are generated as a superposition of high-order Bessel modes and have a closed-form expression relating the design of the phase mask to the rotation rate of the beam. The method is used to fabricate helices with different pitches and handedness in the material SU-8. Compared to point-by-point scanning, the method reported here can be used to reduce fabrication time by two orders of magnitude, paving the way for adopting MPP in many industrial applications.

关键词： tunable axial MPP

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Band-structure-engineered high-gain LWIR photodetector based on a type-Ⅱ superlattice

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Light(Science & Applications) 2021年第2期10卷 140-146页

作者： Arash Dehzangi Jiakai Li Manijeh Razeghi center for Quantum Devices Department of Electrical and Computer EngineeringNorthwestern UniversityEvanstonIL 60208USA

The LWIR and longer wavelength regions are of particular interest for new developments and new approaches to realizing long-wavelength infrared(LWIR)photodetectors with high detectivity and high *** photodetectors are highly desirable for applications such as infrared earth science and astronomy,remote sensing,optical communication,and thermal and medical ***,we report the design,growth,and characterization of a high-gain band-structure-engineered LWIR heterojunction phototransistor based on type-Ⅱ *** 1/e cut-off wavelength of the device is 8.0 *** 77 K,unity optical gain occurs at a 90 mV applied bias with a dark current density of 3.2×10^(-7)A/cm^(2).The optical gain of the device at 77 K saturates at a value of 276 at an applied bias of 220 *** saturation corresponds to a responsivity of 1284 A/W and a specific detectivity of 2.34×10^(13)cm Hz^(1/2)/W at a peak detection wavelength of~6.8 *** type-Ⅱ superlattice-based high-gain LWIR device shows the possibility of designing the high-performance gain-based LWIR photodetectors by implementing the band structure engineering approach.

关键词： heterojunction structure high

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A Hybrid Simulation Test Platform for Verifying the Protection Settings of SPS

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Energy and Power engineering 2017年第4期9卷 346-351页

作者： Jianjian Li Luojiang Qian China Ship Development and design center CSIC Wuhan China School of Electrical engineering Wuhan University Wuhan China

To verify the effectiveness and correctness of the protection settings in ring structure Shipboard Power System (SPS), a digital-physical hybrid simulation platform at China Ship Development and design center (CSDDC) has been built, which aims to give double verification effect of design scheme and physical device. The platform consists of eMEGAsim digital simulator, signal power amplifiers and digital-analog interface equipments. With this platform, the multiple protection device of ring structure grid can be accessed to form a close-loop test system. Since eMEGAsim model-simulated faults and actual protection device actions are on real time, the tripping settings of each device as well as their coordinate performance between multiple devices can be verified in this close-loop test.

关键词： Hybrid Simulation Shipboard Power System (SPS) Protection Settings Close-Loop Test Verify

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Stability analysis on tunnels with karst caves using the distinct lattice spring model

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Underground Space 2021年第4期6卷 469-481页

作者： Jianjun Ma Junwei Guan Junfeng Duan Linchong Huang Yu Liang School of Civil engineering Sun Yat-sen UniversityGuangzhou 510275China Southern Marine Science and engineering Guangdong Laboratory(Zhuahai) Guangdong Key Laboratory of Oceanic Civil EngineeringGuangdong Research Center for Underground Space Exploitation TechnologyZhuhai 519082China MOE Key Laboratory of engineering Structures of Heavy Haul Railway(Central South University) Changsha 410075China China Railway Wuhan Survey and design&Institute Co.Ltd Wuhan 430074China School of Aeronautics and Astronautics Sun Yat-Sen UniversityGuangzhou 510006China

The effects of karst caves on tunnel stability were numerically investigated using the distinct lattice spring model(DLSM).The DLSM was validated by investigating the mechanical behavior of Brazilian discs with various sizes of central circular ***,the effects of karst cave on U-shaped tunnel were investigated under various karst caves positions(top,bottom,and right side of the tunnel),tunnelcave distances(0.5-4 times the radius of the tunnel arc),and cave shapes(circular,rectangular flat,and rectangular vertical caves).The failure processes of the tunnel under those various conditions were analyzed and both the failure process and the final failure patterns of the tunnel were *** simulation demonstrated that karst caves around the tunnel could weaken the stability of the tunnel,indicating tunnel-cave distance *** closer the cave to the tunnel,the weaker the tunnel under *** effect was not significant when the tunnel-cave distance(d)was larger than three times the tunnel arc radius(R).In addition,the final failure pattern of the tunnel and its surrounding rock mass were dependent on both the position and the size of the *** larger the cave,the weaker the tunnel and its surrounding rock ***,compared with those cases with top and bottom caves,the tunnel with a right side cave had more impacts on tunnel *** main research finding could help engineers carry out stability analysis on tunnels in karst areas and take effective measures to enhance tunnel stability.

关键词： Stability analysis Tunnel Karst cave Distinct lattice spring model

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Path planning of hyper‐redundant manipulators for narrow spaces

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IET Cyber-Systems and Robotics 2022年第3期4卷 251-263页

作者： Haoxiang Su Manlu Liu Hongwei Liu Jianwen Huo Songlin Gou Qing Su School of Information engineering Southwest University of Science and TechnologyMian YangChina Robot Technology Used for Special Environment Key Laboratory of Sichuan Province Mian YangChina School of manufacturing Science and engineering Southwest University of Science and TechnologyMian YangChina

Compared with the traditional manipulator,the hyper‐redundant manipulator has the advantage of high flexibility,which is particularly suitable for all kinds of complex working ***,the complex space environment requires the hyper‐redundant manipulator to have stronger obstacle avoidance ability and *** order to solve the problems of a large amount of calculation and poor obstacle avoidance effects in the path planning of the hyper‐redundant manipulator,this paper introduces the‘backbone curve’approach,which transforms the problem of solving joint path points into the behaviour of determining the backbone *** the backbone curve approach is used to design the curve that meets the requirements of obstacle avoidance and the end pose,the least squares fitting and the improved space joint fitting are used to match the plane curve and the space curve respectively,and the angle value of each joint of the manipulator is limited by the ***,a fusion obstacle avoidance algorithm is proposed to obtain the joint path points of the hyper‐redundant *** with the classic Jacobian iteration method,this method can avoid obstacles better,has the advantages of simple calculation,high efficiency,and can fully reflect the geometric characteristics of the *** experiments have proven the feasibility of the algorithm.

关键词： convergence dexterous manipulators geometric algebra motion planning

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Bioinspired urchin-like murray carbon nanostructure with protection shell for advanced lithium-sulfur batteries

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Journal of Energy Chemistry 2023年第10期85卷 1-10,I0002页

作者： Ya-Wen Tian Yong Yu Liang Wu Min Yan Wen-Da Dong Chen-Yang Wang Hemdan S.H.Mohamed Zhao Deng Li-Hua Chen Tawfique Hasan Yu Li Bao-Lian Su State Key Laboratory of advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070HubeiChina School of Automotive engineering Xiangyang PolytechnicXiangyang 441050HubeiChina Hubei Key Laboratory of Plasma Chemistry and advanced Materials Hubei Engineering Technology Research Center of Optoelectronic and New Energy MaterialsSchool of Materials Science and EngineeringWuhan Institute of TechnologyWuhan 430205HubeiChina Physics Department Faculty of ScienceFayoum UniversityEl Gomhoria Street63514 FayoumEgypt Cambridge Graphene Centre University of CambridgeCambridge CB30FAUnited Kingdom Laboratory of Inorganic Materials Chemistry(CMI) University of Namur61 rue de BruxellesB-5000 NamurBelgium

Commercial application of lithium-sulfur(Li-S) batteries is hindered by the insulating nature of sulfur and the dissolution of polysulfides. Here, a bioinspired 3D urchin-like N-doped Murray's carbon nanostructure(N-MCN) with interconnected micro-meso-macroporous structure and a polydopamine protection shell has been designed as an effective sulfur host for high-performance Li-S batteries. The advanced 3D hierarchically porous framework with the characteristics of the generalized Murray's law largely improves electrolyte diffusion, facilitates electrons/ions transfer and provides strong chemisorption for active species, leading to the synergistic structural and chemical confinement of polysulfides. As a result,the obtained P@S/N-MCN electrode with high areal sulfur loading demonstrates high capacity at high current densities after long cycles. This work reveals that following the generalized Murray's law is feasible to design high-performance sulfur cathode materials for potentially practical Li-S battery applications.

关键词： Li-S batteries Murray’s law Hierarchically porous framework N-doped carbon Structural-chemical confinement

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