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A monolithic optimal control method for displacement tracking of cosserat rod with application to reconstruction of c. elegans locomotion

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cOMPUTATIONAL MEcHANIcS 2023年第3期71卷 409-432页

作者： Wang, Yongxing Ranner, Thomas Ilett, Thomas P. Xia, Yan cohen, Netta Univ Leeds Sch Comp Leeds W Yorkshire England Univ Leeds Ctr Computat Imaging & Simulat Technol Biomed CIS Leeds W Yorkshire England

This article considers an inverse problem for a cosserat rod where we are given only the position of the centreline of the rod and must solve for external forces and torques as well as the orientation of the cross sections of the centreline. We formulate the inverse problem as an optimal control problem using the position of the centreline as an objective function with the external force and torque as control variables, with meaningful regularisation of the orientations. A monolithic, implicit numerical scheme is proposed in the sense that primal and adjoint equations are solved in a fully-coupled manner and all the nonlinear coefficients of the governing partial differential equations are updated to the current state variables. The forward formulation, determining rod configuration from external forces and torques, is first validated by a numerical benchmark;the solvability and stability of the inverse problem are then tested using data from forward simulations. The proposed optimal control method is motivated by reconstruction of the orientations of a rod's cross sections, with its centreline being captured through imaging protocols. As a case study, we take the locomotion of the nematode, caenorhabditis elegans. In this study we take laboratory data for its centreline and infer its cross-section orientation (muscle locations) with the control force and torque being interpreted as the reaction force, activated by c. elegans' muscles, from the surrounding fluids. This method thus combines the mathematical modelling and laboratory data to study the locomotion of c. elegans, which gives us insights into the potential anatomical orientation of the worm beyond what can be observed through the laboratory data. The paper is completed with several additional remarks explaining the theoretical and technical details of the model.

关键词： Optimal control cosserat rod Finite element c elegans Locomotion

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Porous coP/c derived from metal-organic framework as high-performance anode materials for superior lithium storage

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IONIcS 2023年第5期29卷 2087-2092页

作者： Huang, Binqi Liu, Jiaming Hu, Xingrong Lin, Xing Zhang, Lu Li, Wei Jiangxi Univ Sci & Technol Fac Mat Met & Chem Ganzhou 341000 Peoples R China Yunnan Univ Sch Chem Sci & Technol Kunming 650091 Peoples R China

coP has attracted increasing attention due to its high theoretical capacity for lithium storage. However, coP suffers from a large volume expansion during cycling, which leads to electrode pulverization and poor cycle stability. In addition, the conductivity of coP is poor, resulting in undesirable rate performance. To solve this problem, the coP/c composite was prepared based on the in-situ phosphating heat treatment technology of co-BTc MOF. The as prepared coP/c exhibits a good lithium storage specific capacity and a cycle stability, which is attributed by the synergistic effect of the porous nanostructure and carbon frame. The porous nanostructure of the coP/c allows the electrolyte to easily penetrate into the interior, which increases the number of electrochemical reaction sites while effectively mitigating the volume expansion during lithiation and improving electrical conductivity. Thanks to the special structures, the discharge specific capacity of the Lithium-ion batteries (LIBs) based the coP/c as anode materials is 645.7 mAh g(-1) after 200 cycles at a current density of 200 mA g(-1). This work demonstrates that the coP/c has a great potential as a next generation anode material for LIBs.

关键词： coP c Porous nanostructure Anode materials Lithium-ion batteries

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High temperature flexural strength, microstructure, phase evolution and anti-oxidation mechanism of Al-coated carbon fiber/boron phenolic resin ceramizable composite modified with TiB2 and B4c

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cERAMIcS INTERNATIONAL 2023年第15期49卷 25003-25015页

作者： Deng, Zongyi Yang, Xueyuan Yu, Xiaobo Huang, Zhixiong Zhu, Di Shi, Minxian Wuhan Univ Technol Key Lab Adv Technol Specially Funct Mat Minist Educ Wuhan 430070 Peoples R China Hubei Longzhong Lab Xiangyang 441000 Peoples R China China Aerosp Sci & Technol Corp Hubei Inst Aerosp Chem Technol Xiangyang 441000 Peoples R China

carbon fiber/phenolic resin composites (cF/Ph) have attracted great interests in the field of thermal protection materials for their characteristics of high specific strength and easy manufacturing. However, cF/Ph are inherently susceptible to oxidation failure at elevated temperatures. In this study, a novel Al-coated carbon fiber/ boron phenolic resin ceramizable composite modified with TiB2 and B4c was fabricated by an impregnating and compression molding route. Thermal stability, flexural strength, microstructure and phase evolution of the resulting ceramizable composite were studied. The residue yield at 1400 degrees c and flexural strength after treated at 1400 degrees c for 15min was 90.4% and 53.1 MPa, respectively, which was increased by 15.9% and 532.1% than that without ceramizable fillers. Surface defects generated by matrix pyrolysis were well healed, and Pyc and carbon fibers were covered with dense ceramic layers while the fracture surface was covered with relatively continuous ceramic layers without visible pores. Multiphase ceramics composed of TiB2, TiO2, Tic and Pyc were identified. Furthermore, oxidation failure and anti-oxidation mechanism was revealed based on the aforementioned characterizations and thermodynamic calculation results. Oxidation resistance got enhanced markedly for synergistic effects of oxygen consuming, carbon fixation, oxygen barrier and endothermic effect, which were derived from ceramization reactions between TiB2, B4c, O2, Al and Pyc.

关键词： ceramizable composite B Failure analysis c corrosion Mechanical properties E Thermal applications

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Designed formation of c/Fe3O4@Ni(OH)2 cathode with enhanced pseudocapacitance for asymmetric supercapacitors

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JOURNAL OF cOLLOID AND INTERFAcE ScIENcE 2023年第1期635卷 176-185页

作者： Lv, Hui Xiao, Zuoyi Zhai, Shangru Wang, Xuting Hao, Jingai An, Qingda Dalian Polytech Univ Coll Light Ind & Chem Engn Liaoning Collaborat Innovat Ctr Lignocellulos Bior Liaoning Key Lab Lignocellulose Chem & Biomat Dalian 116034 Peoples R China

The rational design and synthesis of advanced electrode materials are significant for the applications of supercapacitors. Ferroferric oxide (Fe3O4), with its high theoretical capacitance is a renowned cathode material. Nevertheless, its low electronic conductivity and poor cycling stability during a long-term charge/discharge process limit its large-scale applications. In this work, the precise modulation of multiple components was reported to enhance electrochemical performance. The ternary heterostructures were fabricated by wrapping ultrathin nickel hydroxide (Ni(OH)2) nanosheets on the surfaces of Fe3O4 nanoparticles-loaded on sodium carboxymethyl cellulose (cMc)-derived porous carbon, named as c/ Fe3O4@Ni(OH)2. Due to the large specific surface area and excellent conductivity of cMc-derived porous carbon and the abundant reaction sites of Ni(OH)2 nanosheets, the optimized c/Fe3O4@Ni(OH)2-1.0 sample exhibited the highest specific capacitance of 3072F g-1 at a current density of 0.5 A g-1. Furthermore, the assembled asymmetric supercapacitor (ASc) with activated carbon and c/Fe3O4@Ni(OH)2-1.0 as the negative and positive electrodes, respectively, showed an energy density of 123 W h kg-1 at 381 W kg-1, and a long-life stability with an excellent capacitance retention of 90.04 % after 10,000 cycles. The route for preparing composite electrode materials proposed in this work provides a reference for realizing highperformance energy storage devices.(c) 2022 Elsevier Inc. All rights reserved.

关键词： cMc Supercapacitor c Ni(OH)2 nanosheet

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Parameters Optimization of Laser-Grinding chain for Processing Groove of 2.5-Dimensional c/Sic composites

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MATERIALS 2023年第13期16卷 4761-4761页

作者： Liu, Guoyue Wang, Jian chen, Bing Guo, Bing Zhang, Hua Wang, Zhaohui Hunan Univ Sci & Technol Sch Mech Engn Hunan Prov Key Lab High Efficiency & Precis Machin Xiangtan 411201 Peoples R China Hunan Taijia New Mat Technol Co Ltd Changsha 410203 Peoples R China Harbin Inst Technol Ctr Precis Engn Sch Mechatron Engn Harbin 150001 Peoples R China Wuhan Univ Sci & Technol Coll Mech Automat Wuhan 430081 Peoples R China

Aiming at problems such as poor precision of laser processing c/Sic composites, low efficiency of grinding c/Sic composites, and serious wear of grinding wheel, a method of laser-grinding chain processing c/Sic composite groove was proposed in this paper. The method combined the high efficiency characteristic of laser ablating and the high precision characteristic of grinding. The relationship between laser processing parameters and the characteristics of ablative grooves was investigated, and the appropriate laser processing parameters were optimized, and then, to further improve the processing quality of the grooves, the grinding parameters optimization experiments of the grooves of c/Sic composites were carried out. The results showed that the c/Sic composites could be quickly removed by laser processing, and the grooves with relatively good size and shape accuracy could be obtained by laser parameters optimization experiments, but the side wall of the groove still had a certain inclination and the surface quality of the groove was yet poor;meanwhile, the size accuracy, shape accuracy, and surface quality of the grooves were greatly improved by further grinding. In addition, then, through the laser and grinding optimization experiments, the optimized parameters were obtained, where the laser power was 80 W, the scanning speed was 300 mm/s, the scanning frequency was 50 kHz, the scanning spacing was 25 & mu;m, the depth of cut was 30 & mu;m, the liner speed of wheel was 62.832 m/min, and the feed speed was 10 mm/min. With these parameters, the time used to process the groove with the laser-grinding chain was about 23/40 of the grinding process, and the quality of grooves could be guaranteed. Therefore, combined with the optimized process parameters, the laser-grinding chain processing scheme could be used to achieve high efficiency and precision grinding of c/Sic composite grooves.

关键词： c Sic composite laser-grinding chain processing groove feature parameter optimization

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Wear modelling and sealing performance prediction of c/c composite finger seal

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PROcEEDINGS OF THE INSTITUTION OF MEcHANIcAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY 2023年第5期237卷 1142-1155页

作者： Lu, Fei Liu, Jian Pang, Xianjuan Song, chenfei Xu, Zhidong Henan Univ Sci & Technol Sch Vehicle & Transportat Engn Luoyang 471023 Peoples R China Henan Univ Sci & Technol Natl United Engn Lab Adv Bearing Tribol Luoyang Peoples R China China Petr First Construct Corp Ltd Int Engn Branch Luoyang Peoples R China

Due to the high speed and high pressure operating conditions, wear between the finger seal and the rotor is inevitable, and this leads to an increase of leakage clearance and becomes an important factor affecting the seal life. The theory of anisotropic elasticity was employed to describe the mechanical characteristics of the seal material. An improved Archard wear model was proposed to calculate the nodal wear rate, and the local wear direction was also determined. The wear simulation model and procedure were established based on the Arbitrary Lagrangian Eulerian adaptive mesh strategy. The effects of material density, fabric orientation, pressure differential and rotor speed on the wear characteristics of finger seal and the change of leakage clearance caused by wear loss were studied. The results show that the wear first occurs at the heel area of the finger foot bottom and gradually extends to the toe area. c/c (carbon fibre reinforced carbon matrix) composite finger seal with higher material density has smaller leakage clearance and wear depth. With the increase of fabric orientation angle, the wear depth in the heel area of finger foot is smaller, and the circumferential wear area is narrower. The average wear depth of finger seal decreases with the orientation angle. When the orientation angle is 0, the seal leakage clearance is smaller. The increase of pressure differential not only aggravates the seal wear, but also expands the wear area, and also increases the average contact pressure and leakage clearance. Increasing the rotor speed make the wear depth of the heel area of finger foot gradually increase, but the wear area becomes narrower. The average contact pressure decreases and the average leakage clearance increases. This study provides a theoretical method and basis for the prediction and evaluation of the wear life and performance of c/c composite finger seal.

关键词： finger seal c c composite FE simulation wear depth seal leakage

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Effect of Al addition on the single and cyclic ablation properties of c/c-Sic composites

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cERAMIcS INTERNATIONAL 2023年第4期49卷 6262-6269页

作者： Zhang, Haijun Liu, Lei Feng, Wei Guo, Yongchun Han, Qinxin Tang, chengwei Wang, Xinyu Xie, Yixin Xian Technol Univ Sch Mat & Chem Engn Xian 710021 Peoples R China

This article focuses on the damage behavior and mechanism of aluminum addition on reactive melt infiltrated c/ c-Sic composites in single and cyclic ablation environments. Plasma ablation tests were performed on c/c-Sic composites containing 20 wt % and 40 wt % aluminum respectively. coupled with TMA, XRD, SEM and EDS, the results showed that composites with 40 wt % Al had better ablation resistance during the cyclic ablation, while the composites with 20 wt % Al had excellent ablation damage resistance during a single ablation. This difference was due to higher number of microcracks formed inside the composites containing 40 wt % Al than 20 wt % Al, the lower specimen surface temperature during ablation, and the thermal stresses can be released by pore crack expansion during gas reciprocal loading. While in the single continuous loading of gas, the 20 wt % Al composite formed a protective oxide layer with smaller pores and fewer gas and oxygen entry channels, resulting in good resistance to ablation.

关键词： cyclic ablation Al addition c c-Sic Reactive melt infiltration

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Ablation behavior of c/Sic with YSZ and ZrB2 coatings under high-energy laser irradiation

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cERAMIcS INTERNATIONAL 2023年第2期49卷 1700-1709页

作者： Geng, Li cheng, Su Guo, chuchu Wang, Fuyuan Li, Hejun Northwestern Polytech Univ Shaanxi Carbon Carbon Composites Engn Technol Res Xian 710072 Shaanxi Peoples R China Natl Engn Res Ctr Ceram Matrix Composite Manufactu Xian 710000 Shaanxi Peoples R China

carbon fiber-reinforced silicon carbide (c/Sic) composites are important candidates for laser protection materials. In this study, ablation mechanism of c/Sic coated with ZrO2/Mo and ZrB2-Sic/ZrO2/Mo under laser irradiation was studied. ZrB2-Sic multiphase ceramic and ZrO2 ceramic were successfully coated on c/Sic composite by atmospheric plasma spraying technology with Mo as transition layer. Phase evolution and morphology of composite were investigated by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Moreover, ablation behavior of the composite was investigated by laser confocal microscopy. Results showed that ablation mechanism of c/Sic composite was controlled by phase transformation, thermal reaction, and thermal diffusion, with solid-liquid transition of ZrB2 and ZrO2 being dominant factor. Endothermic reaction and good thermal diffusivity of coatings were also important factors affecting ablation performance. Reflectivity effect of ZrO2 coating was limited under high-energy laser irradiation. compared with ZrO2/Mo single-phase-monolayer coating, designed ZrB2-Sic/ZrO2/Mo coating showed better ablation performance, and breakdown time of c/Sic increased from 10 to 40 s. The depletion of liquid phase in molten pool was identified as an important factor responsible for rapid failure of c/Sic. The coating failed when the entire liquid phase was consumed within molten pool, followed by rapid damage of c/Sic substrate. Results of this study can provide theoretical guidance and research ideas for design and application of laser protective materials.

关键词： c Sic Laser protective coating Laser ablation Finite element analysis Thermodynamic analysis

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High capacity adsorption of iodine gas by Ag⁰@c/SiO2 derived from rice husk: synergistic effect between c/SiO2 supports and Ag⁰ sites

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JOURNAL OF RADIOANALYTIcAL AND NUcLEAR cHEMISTRY 2023年第8期332卷 3059-3068页

作者： Xiong, Yingwei Ai, Yanru Wang, Hongxun Wang, Enchao Dan, Hui Ding, Yi Mianyang TeachersCollege Chuanxibei RHS Construct Mianyang Teachers Coll Si Engn Res Ctr Mianyang 621000 Peoples R China Technol Res Inst Ecol Energy Saving Environm Protect & Low Carbon Mianya Mianyang 621010 Peoples R China Southwest Univ Sci & Technol Sch Natl Def Sci & Technol Mianyang 621010 Peoples R China

A series of Ag-0@c/SiO2 adsorbents were prepared using rice husk-based c/SiO2 as supports and applied to capture iodine gas. The results demonstrated that 50%Ag-0@c/SiO2 reached a record high iodine adsorption capacity (788 +/- 25 mg/g) due to the synergistic effect between c/SiO2 supports and Ag-0 sites. The adsorption data of Ag-0@c/SiO2 can be better fitted with the pseudo first order and Langmuir models. The iodine adsorption process included the physical and chemical adsorption. The adsorption mechanism was that Ag-0 reacted with I-2 to form AgI. Owing to the excellent adsorption capacity, Ag-0@c/SiO2 derived from rice husk could be promising iodine gas adsorbents.

关键词： Iodine gas Silver Rice husk c SiO2 Adsorption

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Ta(B, c, N) and (Ta, Mi)(B, c, N) (Mi = Nb, W) ceramics by high-energy ball milling: processing and solution mechanisms

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JOURNAL OF THE AMERIcAN cERAMIc SOcIETY 2023年第1期106卷 699-708页

作者： Guan, Jingyi Li, Daxin Yang, Zhihua Wang, Bingzhu Jia, Dechang Zhou, Yu Harbin Inst Technol Sch Mat Sci & Engn Inst Adv Ceram Harbin 15000 Peoples R China Harbin Inst Technol Key Lab Adv Struct Funct Integrat Mat & Green Mfg Harbin Peoples R China Harbin Inst Technol Chongqing Inst Chongqing Peoples R China

In order to study the solid-solution process between amorphous BcN and metal Ta, Ta(B, c, N), (Ta, Nb)(B, c, N), and (Ta, W)(B, c, N) ceramics were prepared by high-energy ball milling, and their phase composition, microstructures, and binding bonds have been analyzed. The results show that all the three ceramics are hard agglomeration state, formed by stacking of nanoparticles. The mechanical alloying process is accompanied by the formation of chemical bonds, such as B-Ta, N-Ta, c-Ta, and O-Ta for Ta(B, c, N) ceramic, and the order of solid solution is c > N > B. When heated at 1500 degrees c, a second diboride phase precipitates from (Ta, Nb)(B, c, N) ceramic, whereas the second phase of Wc gradually dissolved from (Ta, W)(B, c, N) ceramic. This work provides theoretical and data supporting to analyze the solid-solution process of Ta(B, c, N) ceramic.

关键词： high-energy ball milling microstructure solid solution Ta(B c N) ceramic

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