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Could the Rebound Characteristics of Oblique Impact for SiO2 Particles Represent the Ash Particles?

ACS OMEGA 2024年第9期9卷 10459-10467页

作者： Li, Xue Xie, Jun Dong, Ming Chen, Sheng Dong, Wenjie Wuhan Inst Technol Sch Opt Informat & Energy Engn Wuhan 430205 Peoples R China Dalian Univ Technol Sch Energy & Power Engn Key Lab Ocean Energy Utilizat & Energy Conservat Minist Educ Dalian 116024 Peoples R China Huazhong Univ Sci & Technol Sch Energy & Power Engn State Key Lab Coal Combust Wuhan 430074 Peoples R China Shenyang Aerosp Univ Coll Energy & Environm Shenyang 110136 Peoples R China

Collisions between particles or with a surface have been widely applied, in which the restitution coefficients are the important parameter to describe the particle rebound behavior. SiO2 particles are often used instead of ash particles in theoretical analyses;however, whether this is justifiable has not been confirmed. This paper compares the rebound characteristics of oblique impact for SiO2 particles and ash particles by experimental and theoretical analyses. Based on the rigid-body theory, the tangential restitution coefficients, rebound angle-particle center, and reflection angle-contact path predicted by SiO2 particles are basically in agreement with the experimental results for ash particles, especially at large impact angles. However, there is a slight error at 2.2 m/s as the velocity approaches the critical capture velocity.

关键词： Collisions Deposition Friction Particles Reaction products

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Experimental Study on Compression Failure of Type II Ballastless Track Slab Based on Optical Fiber Sensing

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TRANSPORTATION RESEARCH RECORD 2024年第10期2678卷 1594-1609页

作者： Zhang, Xuebing Quan, Yang Zheng, Zhizhou Wang, Li Cui, Hongtian Xie, Xiaonan Wu, Han Liu, Xiaochun Yang, Delei Wang, Huaping Xiang, Ping Xiangtan Univ Coll Civil Engn Xiangtan Hunan Peoples R China Cent South Univ Sch Civil Engn Changsha Hunan Peoples R China Huanghuai Univ Architecture Engn Coll Zhumadian Henan Peoples R China Lanzhou Univ Coll Civil Engn & Mech Lanzhou Peoples R China City Univ Hong Kong Dept Architecture & Civil Engn Hong Kong Peoples R China

Ballastless track structures are widely employed in high-speed rail networks because of their superior safety and durability. Among the various types of ballastless track, the Type II slab is currently one of the most extensively used and mature technologies in practice. Over the course of its service life, the damage within the ballastless track structure gradually accumulates in response to increased external loads. Therefore, it is crucial to continuously monitor the health condition of the track structure. In this study, a quasi-distributed fiber optic sensing system is adopted to monitor the deformation capacity and force performance of a Type II ballastless track slab under vertical load. The investigation aims to analyze the damage mechanism of the track structure under vertical pressure by assessing the deformation differences among its different components. The findings reveal that the incorporation of vertical reinforcement can enhance the pressure bearing capacity of the cement asphalt mortar layer to a certain extent, subsequently affecting the stress dilation. The stress performance of the ballastless track slab can be effectively monitored using the quasi-distributed fiber optic sensing technology under pressure. The outcomes of this research offer valuable insights for controlling displacement and analyzing damage in ballastless railway systems subjected to compression.

关键词： fiber optic sensing monitoring ballastless track type II slab compressive damage

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Efficiency Improvement of 6.78MHz Metamaterials for WPT System 26

Efficiency Improvement of 6.78MHz Metamaterials for WPT Syst...

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26th International Conference on Electrical Machines and Systems, ICEMS 2023

作者： Yan, Lihui Gao, Huiming Rong, Cancan Liao, Zhijuan Xia, Chenyang Wang, Qiong China University of Mining and Technology Xuzhou China

ISBN: (纸本)9798350317589

There are many applications for wireless power transfer (WPT), but as the transmission distance increases, the magnetic field energy decays and the transmission efficiency drops sharply. In this paper, a focused electromagnetic metamaterial (MM) unit is designed. When the operating frequency is 6.78 MHz, the permeability of the metamaterial unit is negative, and the purpose of focusing the magnetic field is achieved. The WPT system using a 3× 3 array metamaterial was established. Through simulation, the magnetic field diagram and transmission efficiency of WPT system with metamaterial slab varying different transmission distances are obtained. The magnetic field around the Rx coil is significantly improved after adding the MM slab. When the transmitting and receiving coils are 20cm apart, the transmission efficiency of the system is improved the most with 41.03%. © 2023 IEEE.

关键词： Metamaterials

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Study on performance enhancement driven by strain-induced α′ martensite transformation in a metastable dual-phase titanium alloy

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JOURNAL OF MATERIALS RESEARCH AND technology-JMR&T 2024年 30卷 7065-7075页

作者： Ji, Pengfei Xia, Chaoqun Liu, Shuguang Chen, Bohan Li, Bo Zhang, Han Tang, Huaguo Qiao, Zhuhui Shandong Lab Adv Mat & Green Manufacture Yantai Yantai 264006 Peoples R China Chinese Acad Sci Lanzhou Inst Chem Phys State Key Lab Solid Lubricat Lanzhou 730000 Peoples R China Yanshan Univ State Key Lab Metastable Mat Sci & Technol Qinhuangdao 066004 Peoples R China Hebei Univ Technol Sch Mat Sci & Engn Tianjin Key Lab Mat Laminating Fabricat & Interfa Tianjin 300130 Peoples R China Beijing Res Inst Automat Machinery Ind Co Ltd Engn Res Ctr Electrophys Apparat & Applicat Techn Beijing 100120 Peoples R China Henan Univ Sci & Technol Natl United Engn Lab Adv Bearing Tribol Luoyang 471023 Peoples R China

This study improves ductility while maintaining the ultimate tensile strength (UTS) of a Ti-30Zr-5Al-3V alloy without changing chemical composition via microstructural control of the double-phase (alpha+beta). +beta). The deformation mechanism of the alloy is controlled by regulating the volume fraction of the beta phase, resulting in an ultra-high strain hardening capacity that enhances the material's mechanical properties. The water-quenched specimen exhibits an ultra-high strain hardening capacity attributed to the increase in both back and effective stresses as the deformation proceeds. Heterostructure deformation and the accumulation of geometrically necessary dislocations (GNDs) near grain boundaries induce back-stress strengthening. Effective stress strengthening primarily arises from dislocation reinforcement, including the dynamic Hall-Petch effect caused by strain-induced alpha ' martensite transformation (SIMT) and the hindering effect of GNDs migration. The reorientation and merging of alpha grains are inconducive to high strain hardenability. However, a lower beta phase volume fraction in the air-cooled specimen results in less SIMT, and even small strains could lead to significant grain coarsening. High strain hardening rates could not be maintained solely through back stress strengthening, leading to premature material failure. In comparison to the air-cooled specimen, the water-quenched specimen demonstrates a significantly increased ultra-high strain hardening capability, resulting in enhanced uniform elongation (from similar to 3.4 to similar to 9.6%) and overall elongation (from similar to 6.2 to similar to 13.3%) without reducing the UTS.

关键词： Titanium alloys Mechanical properties Deformation mechanisms Transformation-induced plasticity

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Scenario Generation of Renewable Energy Based on Improved Diffusion Model

Scenario Generation of Renewable Energy Based on Improved Di...

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2023 IEEE Sustainable Power and Energy Conference, iSPEC 2023

作者： Li, Sheng Xu, Chuanyu Wei, Lishen Li, Ruijie Ai, Xiaomeng State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

ISBN: (纸本)9798350322699

The large-scale integration of renewable energy into the power system has resulted in increased complexity of its uncertainty. This complexity arises from the rapidly increased renewable energy sites and the intricate spatial-temporal correlations involved. To offer a more precise description of the uncertainty of renewable energy, a scenario generation method based on an improved diffusion model is proposed. This approach can autonomously learn the probability distribution and spatiotemporal correlation of the training data. It utilizes a U-Net model to progressively denoise noise and iteratively generate renewable energy scenarios. Experiments using historical power data from five wind farms and five PV plants in Jiangsu Province show that the training process of the proposed method is more stable compared to existing methods. Moreover, the proposed method achieves higher accuracy in fitting probability distribution and captures the spatial correlation between multiple sites more accurately. © 2023 IEEE.

关键词： diffusion Model renewable energy scenario generation unsupervised learning

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Studies of beam ion confinement to enhance plasma performance on EAST

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Plasma Science and technology 2024年第12期26卷 18-30页

作者： Jing FU Juan HUANG Jinfang WANG Limin YU Cheonho BAE Jiafeng CHANG Kaiyang HE Yueheng HUANG Pan LI Wei GAO Yifei JIN Tianqi JIA Minrui WANG Yanxu SUN Chang SHI Shusong WANG Xihui WANG Hailin ZHAO Yifeng ZHENG Yahong XIE Guoqiang ZHONG Qing ZANG Haiqing LIU Jinping QIAN Hefei Institutes of Physical Science Chinese Academy of SciencesHefei 230031People’s Republic of China University of Science and Technology of China Hefei 230026People’s Republic of China Department of Physics East China University of Science and TechnologyShanghai 200237People’s Republic of China Anhui University Hefei 230601People’s Republic of China

A key physics issue for achieving steady-state high-performance plasmas on EAST tokamak is to decrease beam-ion losses to improve plasma confinement during neutral beam injections(NBIs).To decrease the beam losses,previous counter-I_(p)NBI injections are upgraded to co-I_(p)*** shows that due to the reversed direction of drift across the flux surfaces caused by the pitch angle,the beam prompt loss fraction decreases from about 49%to 3%after the ***,because of the change of entire beam path,beam shine-through(ST)loss fraction for counter-I_(p)tangential and counter-I_(p)perpendicular injections is reversed to co-I_(p)tangential and co-I_(p)perpendicular injections,*** to the change in the initial trapped-confined beam ion fraction caused by the peaked pitch profiles,the losses induced by toroidal ripple field are also reversed after the *** further improve the beam-ion confinement under the present NBI layout,the amplitudes of toroidal field are increased from 1.75 to 2.20 *** shows that,due to the smaller orbit width and peaked pitch angle profile,the beam prompt loss power is lower with higher toroidal *** to the synergy of higher initial trapped-confined beam ion fraction and narrower Goldston-White-Boozer(GWB)boundary,the loss induced by ripple diffusion is higher with higher toroidal *** combined effect of beam ST loss,prompt loss and ripple loss,contributes to the increase in beam ion *** decrease in beam loss power enhances beam heating efficiency,especially the fraction of beam heating ***,comparison between simulation and measurement by^(235)U fission chamber(FC)indicates that the increase in neutron rate is mainly contributed by improvement of beam-ion *** study can provide potential support for beam operation and high-T_(i)experiment on EAST tokamak.

关键词： beam-ion losses plasma performance neutral beam injections tokamak

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Decomposition and prediction of hydrodynamic loads on a floating counter-rotating tidal turbine under surge motion

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PHYSICS OF FLUIDS 2024年第10期36卷

作者： Sun, Jiyuan Miao, Hongjiang Wang, Pengzhong Huang, Bin Wang, Yu Zhejiang Univ Ocean Coll Zhoushan 316021 Peoples R China Hangzhou Dalu Ind Co Ltd Hangzhou 311227 Zhejiang Peoples R China Zhejiang Univ Ocean Res Ctr Zhoushan Zhoushan 316021 Peoples R China Tonglu MOULD Machinery Mfg Co Ltd Hangzhou 310027 Peoples R China

In the actual marine environment, the hydrodynamic characteristics of floating counter-rotating tidal turbines (FCRTTs) are influenced by the motion responses of their carrier platforms. Therefore, accurately analyzing and predicting hydrodynamic loads under the motions of FCRTTs are crucial. In this paper, a fitting formula for hydrodynamic loads of FCRTTs applicable to rotational motion is derived. Then, the effects of surge amplitude, surge frequency, and tip speed ratio on the hydrodynamic loads of an FCRTT are also calculated. It is found that the instantaneous load fluctuation of the rear rotor is more severe than that of the front rotor. However, the average torque of both rotors is similar, which can effectively enhance the operational stability of the FCRTT. Additionally, the hydrodynamic loads are decomposed into average hydrodynamic force, damping force, and added mass force based on the least squares method. A fitting formula for the hydrodynamic loads applicable to different surge conditions is derived, incorporating 11 hydrodynamic coefficients. The results indicate that the damping coefficients n(P)(0) and n(T)(0) play a dominant role in the fluctuation amplitude of the hydrodynamic loads. Finally, an effective and fast prediction model for various hydrodynamic coefficients is successfully established using the three-dimensional radial basis function. The relative errors between the predicted peak values of all performance coefficients and the values calculated using the computational fluid dynamics (CFD) method are within -3.5%. This paper provides important guidance for engineering design and load prediction of FCRTTs. Moreover, the predictive methodology can be extended for application to other single-degree-of-freedom and couple motions.

关键词： Damping

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Low-Cost Halide Electrolytes Li2+x Hf1-x Fex Cl6 with Superior Ionic Conductivities for All-Solid-state Lithium-Metal Based Batteries

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ACS SUSTAINABLE CHEMISTRY & engineering 2024年第18期12卷 7012-7025页

作者： Tuo, Kaiyong Yin, Fusheng Sun, Chunwen China Univ Min & Technol Beijing Sch Chem & Environm Engn Beijing 100083 Peoples R China

All-solid-state batteries (ASSBs) employing inorganic solid electrolytes have been considered as promising candidates for next generation energy storage owing to their intrinsic safety performance and high energy density. Designing highly ionically conductive and (electro)chemically stable inorganic solid electrolytes utilizing cost-effective materials is of vital importance for the development of practical ASSBs. Herein, we report a series of new lithium-conducting superionic halides Li2+xHf1-xFexCl6 that are free of rare-earth elements with high ionic conductivities up to 0.91 mS cm(-1) at 30 degrees C by aliovalent substitution with low-cost and earth-abundant Fe elements. By means of complementary characterization techniques and bond-valence site energy (BVSE) calculations, we gain insights into the influence of aliovalent doping engineering on the local structural environment and the underlying lithium-ion transport properties of Fe3+-substituted Li2HfCl6. Importantly, it is demonstrated that the prevalently existent distortion of octahedral structure and redistribution of the lithium ion induced by the aliovalent substitution strongly benefits the transport properties. Notably, the formation of infinitely 3D connected lithium-ion migration pathways comprised of a directly connected face-sharing octahedron along the c direction is revealed by structural analysis and theoretical calculations. Additionally, owing to the intrinsic oxidation tolerance of Fe3+-substituted Li2HfCl6, the fabricated bulk-type ASSBs with uncoated LiCoO2 deliver an outstanding electrochemical performance.

关键词： halide electrolytes ionic conductivity aliovalentdoping mechanochemical milling all-solid-statebatteries

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Evaluation on steel corrosion risk of seawater sea sand concrete with low water-to-binder ratio by electrochemical measurement

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CONSTRUCTION AND BUILDING MATERIALS 2024年 417卷

作者： Zhao, Yifan Li, Huang Hu, Xiang Shi, Caijun Hunan Univ Coll Civil EngnKey Lab Bldg Safety & Energy Effic Int Sci & Technol Innovat Ctr Green & Adv Civil En Key Lab Green & Adv Civil Engn Mat & Applicat Tech Changsha 410082 Peoples R China China Construction Fifth Engn Bur Co Ltd Changsha 410004 Peoples R China

The primary challenge in utilizing cement concrete mixed with seawater and/or sea sand lies in the risk of steel corrosion. In this study, the Cl-/OH- ratio of pore solution of seawater sea sand concrete (SSSC) with low waterto-binder (w/b) ratio is evaluated by water extraction technique. Half-cell potential (Ecorr) and corrosion current density (Icorr) serve as parameters for characterizing the electrochemical properties and corrosion risk of steel rebars embedded in SSSC with w/b ratios of 0.2 and 0.4. The findings reveal that the steel corrosion resistance of SSSC with a w/b ratio of 0.2 is significantly higher than specimens with w/b ratio 0.4 due to the lower oxygen, moisture contents and denser microstructure. Over a monitoring period up to 3 years, the results of Ecorr and Icorr confirm that the corrosion rate of steel rebars in SSSC with low w/b ratio is notably lower than that in ordinary SSSC. The corrosion of steel rebar in 0.2-C occurs at initial curing ages and then the steel rebar gradually enters into the passivation state, while the corrosion reaction of steel rebar in 0.4-C continuously proceeds during the whole testing period. Notably, the values of Ecorr and Icorr for SSSC with low w/b ratio exhibit an exponential relationship, while they display a rough linear correlation in ordinary SSSC, influenced by the varying corrosion states of the steel rebar. The results in this study can help to form a theory basis for the development of lifetime prediction model of reinforced UHPC.

关键词： Seawater sea sand concrete (SSSC) Low water -to -binder ratio Electrochemical property Steel corrosion

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Flexible pressure sensors based on reduced graphene oxide @ porous silicone elastomers with good resolution and wide working range

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SENSORS AND ACTUATORS A-PHYSICAL 2024年 366卷

作者： Li, Qichao Chen, Di Miao, Jianmin Yu, Jiajie Chen, Changxin Liu, Yamin Shanghai Jiao Tong Univ State Key Lab Met Matrix Composites Shanghai 200240 Peoples R China Shanghai Jiao Tong Univ Natl Key Lab Adv Micro & Nano Manufacture Technol Shanghai 200240 Peoples R China Shanghai Jiao Tong Univ Frontiers Sci Ctr Transformat Mol Sch Chem & Chem Engn Shanghai 200240 Peoples R China Natl Engn Res Ctr Nanotechnol Shanghai 200241 Peoples R China South China Univ Technol Key Lab Polymer Proc Engn Minist Educ GuangZhou 510640 Peoples R China Beihang Univ Hangzhou Innovat Inst Key Lab Intelligent Sensing Mat & Chip Integrat Te Hangzhou Peoples R China Shanghai Jiao Tong Univ Sch Elect Informat & Elect Engn 800 Dongchuan Rd Shanghai 200240 Peoples R China

Current flexible piezoresistive pressure sensors still face challenges, such as poor stability and a limited detection range, making it difficult to accurately discern small-scale pressures in the Pa or MPa range when meeting sudden pressure events. To tackle the above issues, this study presents the development of a competent sensor composed of porous conductive elastomer and laser-induced graphene electrodes. The substrate of the composite elastomer is a porous silicone elastomer obtained by the additive reaction using template methods, and the conductive filler consisting of reduced graphene oxide is synthesized through an eco-friendly approach. We demonstrated that the sensors fabricated here have the ability to precisely resolve pressures from 542 Pa to 1.5 MPa with long -term stability, as well as the detection of subtle signals, such as pulse pulsation and throat vibrations. Above all, such sensors have great potential in the application of human -machine interaction.

关键词： Pressure sensor Graphene Wide working range Wearable application Human -machine interaction

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