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Shaking table test for externally-hung self-centering rocking wall structure

BULLETIN OF EARTHQUAKE ENGINEERING 2021年第2期19卷 863-887页

作者： Li, Xiangmin Zhang, fuwen Tian, Kun wang, Zhuolin Jiang, Lu Dong, Jinzhi Shanghai Res Inst Bldg Sci Co Ltd Shanghai Key Lab Engn Struct Safety Room 211Bldg Jianke75 South Wanping Rd Shanghai 200032 Peoples R China

This paper proposes an innovative externally-hung self-centering rocking wall (ESRW) structural system for retrofitting existing reinforced concrete structures. Reinforced corbels are installed on the columns of an existing structure to which rocking walls having unbonded post-tensioned tendons are connected using H-shaped connectors. The seismic performance and self-centering ability of the ESRW were investigated through a series of shaking table tests. For comparison, an unretrofit control structure (UCS) was also tested. The UCS was severely damaged under peak ground acceleration (PGA) = 1.2 g test conditions: some reinforcing bars were fractured and the UCS was close to collapse. For the ESRW, the damage was significantly reduced: there were only minor cracks appearing at PGA = 1.5 g test conditions and no damage appeared at the corners of the rocking walls. The maximum story drift and residual deformation of the ESRW were reduced 88% and 92%, respectively, relative to the UCS test. The ESRW structure showed desirable seismic performance and self-centering characteristics during shaking table tests.

关键词： Self-centering structure Rocking wall Shaking table test Dynamic response Externally-hung

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Experimental study on longitudinal embedding performance of bolted engineered bamboo connections

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CONSTRUCTION AND BUILDING MATERIALS 2024年 411卷

作者： Leng, Yubing wang, Mingqian Xu, Qingfeng Harries, Kent A. Zhang, fuwen Liu, Kewei Shanghai Res Inst Bldg Sci Co Ltd Shanghai Key Lab Engn Struct Safety Shanghai 200032 Peoples R China Univ Pittsburgh Dept Civil & Environm Engn Pittsburgh PA 15260 USA Int Bamboo & Rattan Org Beijing 100102 Peoples R China 75 South Wanping Rd Shanghai Peoples R China

This paper summarizes the experimental results of longitudinal embedding tests of bolted engineered bamboo connections. Six groups of bolted engineered bamboo connection specimens were prepared and tested monotonically up to failure. Test variables were bolt diameter and type of engineered bamboo: laminated bamboo or bamboo scrimber. Connection stiffness and embedding strength of the specimens of bamboo scrimber were greater than those of the specimens of the laminated bamboo - reflecting the difference in material density. Embedding strength of the laminated bamboo was insensitive to bolt diameter whereas embedding strength of the bamboo scrimber decreased with an increase of the bolt diameter. It was shown that in order to accurately model bolt embedding into bamboo, a foundation model is required. Reduction factors for strength and modulus for such a model were calibrated using experimental results. A parametric study addressing friction and foundation model size is presented.

关键词： Engineered bamboo Bolted connection Embedding performance Calibration of foundation model

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Non-Radiative Recombination Energy Losses in Non-Fullerene Organic Solar Cells

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ADVANCED FUNCTIONAL MATERIALS 2022年第19期32卷 2111855-2111855页

作者： He, Dan Zhao, fuwen wang, Chunru Lin, Yuze Cent South Univ Coll Chem & Chem Engn Changsha 410083 Peoples R China Chinese Acad Sci Beijing Natl Lab Mol Sci CAS Key Lab Organ Solids Inst Chem Beijing 100190 Peoples R China Chinese Acad Sci Lab Mol Nanostruct & Nanotechnol Inst Chem Beijing 100190 Peoples R China

Impressive short-circuit current density and fill factor have been achieved simultaneously in single-junction organic solar cells (OSCs) with the emergence of high-performance non-fullerene acceptors. However, the power conversion efficiencies (PCEs) of OSCs still lag behind those of inorganic and perovskite solar cells, mainly due to the modest open-circuit voltage (V-OC) imposed by relatively large energy loss (E-loss). Generally, E-loss in solar cells can be divided into three parts. Among them, Delta E-1 is inevitable for all photovoltaic cells and depends on the optical bandgap of solar cells, while radiative recombination energy loss, Delta E-2, in OSCs can approach the negligible value via finely matching donor with acceptor material in the blend. The relatively large non-radiative recombination energy loss, Delta E-3, becomes the main barrier to further reduce E-loss and thus enhance PCE in non-fullerene acceptor-based OSCs. In this review, the recent studies and achievements about Delta E-3 in non-fullerene acceptor-based OSCs have been summarized from the aspects of material design, morphology manipulation, ternary strategy, mechanism, and theoretical study. It is hoped that this review helps to get a deep understanding and boost the advance of Delta E-3 study in OSCs.

关键词： energy loss nonfullerene acceptors non-radiative recombination organic photovoltaics organic solar cells

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Tilt Angle Monitoring and Cable Controlling of Holding Pole via FEA and SR-GRU 1

Tilt Angle Monitoring and Cable Controlling of Holding Pole ...

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1st International Conference on Cyber-Energy Systems and Intelligent Energy, ICCSIE 2022

作者： Zheng, fuwen Chen, Jin Jiang, Bin Wu, Xiaoming Chen, Menggang Shi, Yawei Li, Huaqing wang, Huiwei Construction Branch State Grid Chongqing Electric Power Company Chongqing China State Grid Chongqing Electric Power Company Chongqing China Southwest University College of Electronics and Information Engineering Chongqing China

ISBN: (纸本)9781665452151

The holding pole is a kind of special lifting machinery, which is widely used in the erection of power transmission tower. The holding pole belongs to the highrise structure, its stability problem is particularly prominent. Due to the high safety requirements, it is particularly important to conduct in-depth mechanical analysis before design, construction and application. For the holding pole, it has been adopted the balanced lifting as far as possible, however, the construction process will inevitably appear unbalanced lifting. Therefore, two working conditions for the holding pole, namely balanced lifting and unbalanced lifting, are discussed based on the Finite Element Analysis (FEA) in this paper. In addition, introducing the Sparse Residual (SR) learning method to accelerate the training of the applied Gated Recurrent Unit (GRU) network and avoid over-fitting, which can provide the advanced interfere for the unbalanced lifting through the real-time series data collected by accelerometer sensor. Finally, the experimental results from a project case verify the efficiency and robustness of proposed approaches. © 2023 IEEE.

关键词： Finite element method

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Effects of alloying elements on the interfacial segregation of bismuth in tin-based solders

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MATERIALS TODAY COMMUNICATIONS 2023年 35卷

作者： Yan, Jiasi Xiao, Wei wang, Jianwei Zhang, fuwen Li, Xiaowu He, Huijun wang, Ligen China GRINM Grp Co Ltd State Key Lab Nonferrous Met & Proc Beijing 100088 Peoples R China GRIMAT Engn Inst Co Ltd Beijing 101407 Peoples R China Gen Res Inst Nonferrous Met Beijing 100088 Peoples R China Northeastern Univ Sch Mat Sci & Engn Dept Mat Phys & Chem Key Lab Anisotropy & Texture MatMinist Educ Shenyang 110819 Peoples R China Beijing COMPO Adv Technol Co Ltd Beijing 101407 Peoples R China Beijing GRIPM Adv Mat Res Inst Co Ltd Beijing 101407 Peoples R China

Sn-Bi solders are potential candidates for replacing traditional lead-based solders in electronic packaging due to their low melting points, superior wettability, and mechanical properties. The grain coarsening due to the interfacial Bi segregation is a vital issue that affects the reliability of Sn-Bi solder joints. Through first-principles calculations, this study systematically revealed the effects of different alloying elements on the interfacial segregation of Bi towards Sn(100) surface. Bi tends to segregate to the top-surface of Sn due to the formation of vacancies on Sn surface. However, doping alloying elements into the Sn-Bi solders could effectively suppress the interfacial Bi segregation. The presence of elements such as Pd, Pt, and Au located at the adjacent surface layer of Bi could inhibit the Bi precipitation, by apparently increasing the segregation energies of Bi to the Sn surface. The results can be interpreted by the enhanced bond orders and charge transfer between Bi, alloying elements, and their neighboring Sn atoms. This study could provide valuable insights into the design of multi-component Sn-Bi solders with minor alloying elements doping in the future.

关键词： Sn-Bi solders Bi segregation Alloying element doping First-principles

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Coupling and environmental implications of in situ formed biogenic Fe-Mn minerals induced by indigenous bacteria and oxygen perturbations for As (III) immobilization in groundwater

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SCIENCE OF THE TOTAL ENVIRONMENT 2023年第Part2期858卷 159884页

作者： Zhao, Xinxin Xie, Zuoming Liu, Taikun Li, Ping Pei, fuwen wang, Linan China Univ Geosci Sch Environm Studies Wuhan 430074 Peoples R China China Univ Geosci State Key Lab Biogeol & Environm Geol Wuhan 430074 Peoples R China Linyi Vocat Univ Sci & Technol Linyi 276000 Peoples R China South China Univ Technol Sch Environm & Energy Guangzhou 510006 Peoples R China

Iron (Fe)-manganese (Mn) minerals formed in situ can be used for the natural remediation of the primary poor -quality groundwater with coexistence of arsenite [As(III)], Mn(II), and Fe(II) (PGAMF). However, the underlying mechanisms of immobilization and coupling of As, Mn, and Fe during in-situ formation of Fe-Mn minerals in PGAMF remains unclear. The simultaneous immobilization and coupling of arsenic (As), Mn, and Fe in PGAMF during in-situ formation of biogenic Fe-Mn minerals induced by O-2 perturbations and indigenous bac-teria (Comamonas sp. RM6) were investigated at the different molar ratios of Fe(II):Mn(II) (1:1, 2:1, and 3:1). Compared with systems without Fe(II) in the presence of Mn(II), the coexisted Fe(II) significantly enhanced Mn(II) bio-oxidation and mineral precipitation, resulting in As immobilization increased by 5, 7, and 7 times at initial Fe(II) concentration of 0.3, 0.6, and 0.9 mM, respectively. Moreover, the As(III) immobilization effi-ciencies in Mn(II) and Fe(II) mixed system at initial Fe(II) concentration of 0.3, 0.6, and 0.9 mM were 73%, 91%, and 92%, respectively, that were significantly higher than those of single Fe(II) system (30%, 59%, and 74%) and those of single Mn(II) system (12% ), indicating that Fe(II) and Mn(II) oxidation synergically enhanced As(III) immobilization. This was mainly attributed to the formation and As adsorption capacity of bio-genic Fe-Mn minerals (BFMM). The formed BFMM significantly facilitated simultaneous immobilization of Fe, Mn, and As in PGAMF by oxidation, adsorption, and precipitation/coprecipitati on, a coupling of biological, physical, and chemical processes. Fe component was mainly responsible for As fixation, and Mn component dominated As(III) oxidation. Based on the results from this work, biostimulation and bioaugmentation techniques can be developed for in-situ purification and remediation of PGAMF. This work provides insights into the simultaneous immobilization of pollutants in PGAMF, as w

关键词： Oxygen perturbations Indigenous bacteria Fe-Mn minerals As immobilization As-rich groundwater

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Cu@Sn@Ag core-shell particles preform for power device packaging under harsh environments

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JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS 2021年第11期32卷 14703-14714页

作者： Liu, Jiahao Liu, Hao Yu, fuwen wang, Xinjie wang, Jianqiang Hang, Chunjin Chen, Hongtao Li, Mingyu Harbin Inst Technol Shenzhen Dept Mat Sci & Engn Shenzhen 518055 Guangdong Peoples R China China Elect Prod Reliabil & Environm Testing Res Guangzhou 510610 Peoples R China Beijing Santel Technol & Trading Corp Beijing 100854 Peoples R China Harbin Inst Technol State Key Lab Adv Welding & Joining Harbin 150001 Peoples R China

This paper presents a novel die attach material for power device packaging based on transient liquid phase (TLP) bonding. Through two-step electroless plating, the Cu@Sn@Ag particles were prepared, and realize interconnection with Cu Substrates after being compressed into preform. Due to the large specific surface area of the core-shell particles, the reflow time can be reduced to 15 min at a low temperature of 250 degrees C under a pressure of 3 MPa to form high-remelting-point intermetallic compounds (IMCs), which can withstand a high temperature of at least 475 degrees C. Due to the protection of the Ag coating, the Cu@Sn@Ag particles exhibited excellent oxidation resistance, and the bonding process can be carried out in the atmosphere. Then, the service reliability of the bondlines was evaluated in harsh environments, such as high temperature and humidity, high temperature storing, and thermal shock. The average resistivity of the bondlines was increased from 4.6 +/- 1.4 to 8.5 +/- 3.8 mu omega cm after being stored at high temperature (85 degrees C) and high humidity (85% RH) environment for 14 days. After storing at 300 degrees C for 15 days, the porosity of bondline increased from 6.8 to 10.8%, and the average shear strength decreased from 30.5 +/- 6.3 to 22.3 +/- 5.6 MPa. After thermal shock between - 40 and 125 degrees C for 500 cycles, the bonding rate decreased from 99.9 to 84.2%. Moreover, the short-circuit time of electrochemical migration under 60 V voltage was extended to 145 s. The bondline based on the novel core-shell particles exhibited excellent performance as a die attach material under harsh environments.

关键词： Optical and Electronic Materials Characterization and Evaluation of Materials

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Diffusion coefficient measurement and atomic mobility assessment for bcc Ti-V-Fe ternary alloys

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CALPHAD-COMPUTER COUPLING OF PHASE DIAGRAMS AND THERMOCHEMISTRY 2023年第1期82卷

作者： Zhou, Shihang Xu, Guanglong Tao, Xiaoma wang, Jiang Chen, fuwen Cui, Yuwen Nanjing Tech Univ Coll Mat Sci & Engn Nanjing 211816 Peoples R China Guangxi Univ Sch Phys Sci & Technol Nanning 530004 Peoples R China Guilin Univ Elect Technol Guangxi Key Lab Informat Mat Guilin 541004 Peoples R China

Diffusion behaviors in bcc Ti-V-Fe ternary alloys have been investigated at 1273 K and 1473 K by the diffusion couple technique. The composition-distance profiles have been retrieved from Electron Probe MicroAnalysis (EPMA) and analytically represented by the ERror Function EXpansion (ERFEX), and then the ternary inter-diffusion and impurity diffusion coefficients have been extracted by Whittle-Green and generalized Hall methods, respectively. The extracted inter-diffusion coefficients of D TiVV and D TiFeFe range from 0.89 x 10-13 m2/s to 1.86 x 10-13 m2/s and from 1.33 x 10-12 m2/s to 1.76 x 10-12 m2/s, respectively, at 1273K, and from 6.41 x 10-13 m2/s to 15.98 x 10-13 m2/s and from 82.46 x 10-13 m2/s to 147.08 x 10-13 m2/s at 1473K. D TiVV exhibits the similar compositional variation at both temperatures, which decrease with decreasing Fe and minimize at the Ti-V binary. D Ti FeFe has the maximum value at Ti-corner and eventually decreases with the increasing V and Fe at 1273K, but has the maximum value at Fe-rich Ti-Fe binary and decreases with the increasing V. The atomic mobility parameters of Ti-V, Ti-Fe and V-Fe binary systems have been revised to associate with the lasted ternary interaction parameters in thermodynamics. The ternary atomic mobility parameters for diffusion have been assessed for the first time by reproducing the extracted diffusion coefficients. The composition-distance profiles and the diffusion paths have been successfully reproduced by using the optimized atomic mobility pa-rameters showing a consistency with the experimental data and indicating the accuracy of this work.

关键词： Diffusion coefficient Atomic mobility Ti-V-Fe alloys CALPHAD technique

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Rapper: A Parameter-Aware Repair-in-Memory Accelerator for Blockchain Storage Platform

Rapper: A Parameter-Aware Repair-in-Memory Accelerator for B...

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IEEE Symposium on High-Performance Computer Architecture

作者： Chenlin Ma Yingping wang fuwen Chen Jing Liao Yi wang Rui Mao College of Computer Science and Software Engineering Shenzhen University

Blockchain storage platforms reward storage nodes for keeping user-uploaded data for a certain amount of time. These storage nodes are unstable and can go online or offline unpredictably at any time, leading to potential data loss. To prevent data loss, blockchain storage platforms adopt erasure codes on user-uploaded encrypted data. Data repair processes will be performed to recover the lost data. However, the data repair processes heavily rely on time-consuming erasure coding algorithms, mainly consisting of vector-matrix multiplications. The emerging processing-in-memory technique can efficiently speed up the processing of vector-matrix multiplications. It can be integrated into blockchain storage platforms to solve the data repair issue. This paper presents Rapper, a parameter-aware repair-inmemory accelerator for blockchain storage platforms. Rapper utilizes the computing power of emerging processing-in-memory architecture so that data repair processes can be processed in a parallel manner and the overall efficiency can be improved significantly. Specifically, at the hardware level, the ReRAM memory is reorganized into our proposed double bank, XRU, XGroup, and ReRAM crossbars structure. At the software level, a parallel decoding/encoding strategy is proposed to fully exploit the internal parallelism of ReRAM. We also propose an adaptive parameter-aware mapping to handle various sizes of stripes. To demonstrate the viability of the proposed technique, a representative blockchain storage project Storj is adopted as the default storage infrastructure. Experimental results show that Rapper can achieve a 1.96 × speedup on average compared to the representative scheme.

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FASTERMOE: Modeling and Optimizing Training of Large-Scale Dynamic Pre-Trained Models 22

FASTERMOE: Modeling and Optimizing Training of Large-Scale D...

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27th ACM SIGPLAN Symposium on Principles and Practice of Parallel Programming (PPoPP)

作者： He, Jiaao Zhai, Jidong Antunes, Tiago wang, Haojie Luo, fuwen Shi, Shangfeng Li, Qin Tsinghua Univ Beijing Peoples R China

ISBN: (纸本)9781450392044

The current trend in deep learning is to scale models to extremely large sizes with the objective of increasing their accuracy. Mixture-of-Expert (MoE) is the most popular pretrained model that makes feasible the training of models with parameters beyond trillion-scale. Thanks to the dynamic activation of experts, i.e., shallow layers specialized in certain domains, it allows for sparse training of bigger models, removing the linearity between model size and computation. However, different from traditional deep learning models, it draws huge challenges to the efficiency of these training systems, including dynamic load imbalance, inefficient synchronous execution mode, and congested all-to-all communication. To address these challenges, we first propose a performance model that can both accurately predict the latency of different operations o f a specific training task, and intuitively analyze its end-to-end performance via a novel roofline-like model. Then, guided by this model, we invent a dynamic shadowing approach to cope with load imbalance, and a smart fine-grained schedule that splits different operations and executes them concurrently. We design a congestion-avoiding expert selection strategy that relieves network congestion for the lower latency of iterations, when modification of expert selection is allowed. We implement and integrate the above optimizations as a general system, FASTERMOE, empowering efficient distributed MoE model training. FASTERMOE is evaluated on different cluster systems using up to 64 GPUs. It achieves 1.37x - 17.87x speedup compared with state-of-the-art systems for large models, including ZeRO, GShard, and BASE Layer. Source code of FASTERMoE is now available at https://***/thu-pacman/FasterMoE.

关键词： Distributed Deep Learning Parallelism Performance Modeling

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