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Switching Frequency Improvement of a High Speed on/off Valve Based on Pre-excitation Control Algorithm

Chinese Journal of Mechanical Engineering 2024年第4期37卷 94-106页

作者： Qi Zhong Xiaotian Li Yongxin Mao Enguang Xu Tiwei Jia Yanbiao Li Huayong Yang College of Mechanical Engineering Zhejiang University of TechnologyHangzhou 310023China State Key Laboratory of Fluid Power and Mechatronic Systems Zhejiang UniversityHangzhou 310027China Key Laboratory of Special Purpose Equipment and Advanced Processing Technology Ministry of Education and Zhejiang ProvinceZhejiang University of TechnologyHangzhou 310023China

The high-speed on/off valve(HSV)serves as the fundamental component responsible for generating discrete fluids within digital hydraulic *** the switching frequency of the HSV increases,the properties of the generated discrete fluid approach those of continuous ***,a higher frequency response characteristic of HSV is the key to ensure the control accuracy of digital hydraulic ***,the current research mainly focuses on its dynamic performance,but neglect its *** paper presents a theoretical analysis demonstrating that the FRC of the HSV can be enhanced by minimizing its switching *** maximum switching frequency(MSF)is mainly determined by opening dynamic performance when HSV operates with low switching duty ratio(SDR),whereas the closing dynamic performance limits the MSF when HSV operates with high *** upon these findings,the pre-excitation control algorithm(PECA)is proposed to reduce the switching time of the HSV,and consequently enhance its *** results demonstrate that PECA shortens the opening delay time of HSV by 1.12 ms,the closing delay time by 2.54 ms,and the closing moving time by 0.47 ms in comparison to the existing advanced control *** a result,a larger MSF of 417 Hz and a wider controllable SDR range from 20%to 70%were achieved at a switching frequency of 250 ***,the proposed PFCA in this paper has been verified as an effective and promising approach for enhancing the control performance of digital hydraulic systems.

关键词： High speed on/off valve Switching frequency Pre-excitation Dynamic performance Switching duty ratio

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Hierarchically Macroporous Zeolite ZSM-5 Microspheres for Efficient Catalysis

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Chemical Research in Chinese Universities 2024年第4期40卷 704-711页

作者： ZHENG Mingdan CHEN Ya LIU Zhan LYU Jiamin YE Bo SUN Ming-Hui CHEN Li-Hua SU Bao-Lian State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan430070P.R.China Laboratory of Inorganic Materials Chemistry(CMI) University of Namur5000NamurWalloniaBelgium

Hollow zeolite microspheres have recently attracted much attention for their applications in catalysis,microreactors and ***,we present hierarchically structured zeolite ZSM-5 microspheres with unique,abundant macropores that allow more efficient use for *** hierarchically macroporous zeolite ZSM-5 microspheres are synthesized under the assistance of water/oil emulsions and using polystyrene nanospheres as *** zeolite microsphere is assembled by uniform hollow zeolite *** large inner cavities and thin zeolite shells lead to smaller diffusion channel and higher improved accessibility to active sites,contributing to high catalytic performance in the catalytic conversion of benzyl alcohol in *** novel zeolite microspheres with impressive performance will be applied to numerous other industrial catalytic reactions.

关键词： Hierarchically porous structure Hollow structure Microsphere Zeolite ZSM-5 Alkylation

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Preparation and Mechanical Properties of Zirconia Ceramics Doped with Different Y_(2)O_(3)Contents

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Journal of Wuhan University of technology(materials Science) 2023年第6期38卷 1287-1292页

作者： SONG Yanwei ZHAO Xiaoqing WANG Aiyang XIONG Yan DONG Yanling WANG Weimin State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China School of Materials and Chemical Engineering Hubei University of TechnologyWuhan 430068China

The sintering behavior and mechanical properties of zirconia doped with 2.0mol%-3.0mol%Y_(2)O_(3)were studied by pressure-less *** experimental results show that the densification temperature of zirconia ceramics increases gradually with the decrease of Y_(2)O_(3)doping content by which decreases the sintering driving force due to the lower oxygen vacancy concentration of the ***,the bending strength and fracture toughness of the prepared zirconia ceramics increase with the decrease of Y_(2)O_(3)doping *** can be attributed to the fact that the phase stability of tetragonal zirconia decreases with the decrease of Y_(2)O_(3)doping content,which is easier to induce"phase transformation toughening"and dissipate impact *** relative density,bending strength and fracture toughness of 2.0 mol%Y_(2)O_(3)doped zirconia ceramics(2.0Y-ZrO_(2))sintered at 1525℃are 99.00%,1256.65±20.82 MPa and 9.85±0.13 MPa·m^(1/2),respectively.

关键词： yttria-stabilized tetragonal zirconia polycrystal(Y-TZP)ceramics sintering behaviors mechanical properties

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Pressureless densification and properties of high-entropy boride ceramics with B_(4)C additions

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Journal of materials Science & technology 2024年第23期190卷 1-9页

作者： Fawei Wang Liang Xu Ji Zou Jingjing Liu Huayue Liang Wei Ji Weimin Wang Zhengyi Fu Hubei Longzhong Laboratory Wuhan University of Technology Xiangyang Demonstration ZoneXiangyang 441000China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China School of Materials Science and Engineering Wuhan University of TechnologyWuhan 430070China

High entropy boride ceramics have great potential as structural materials serving in extreme ***,their applications are limited by the difficulty of *** the present study,dense(Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))B_(2)ceramics with B_(4)C additions were prepared through pressureless sintering at as low as 1900℃.Calculations based on the CALPHAD approach predict that(Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))B_(2)starts to melt at about 3315℃whilst B_(4)C additions reduce the temperature and broaden the tempera-ture region where solid and liquid *** showed that the introduction of B_(4)C could trigger the densification of(Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))B_(2)at a lower temperature and promote their densification *** relative density of samples with 5 wt%of B_(4)C additions sintered at 1900 and 2000℃was 97.7%and 99.7%,*** the sintering temperature was further increased to 2100℃,the liquid phase was reactively formed,leading to the rapid grain coarsening in samples with B_(4)C *** by well-dispersed B_(4)C grains,the sample with 5 wt%B_(4)C sintered at 2000℃exhibited excellent mechanical properties with the Vickers hardness,flexural strength,and fracture toughness of 21.07±2.09 GPa,547±45 MPa,and 5.24±0.14 MPa m^(1/2),which are comparable or even higher than counterparts sintered under pressure.

关键词： High entropy boride ceramic Microstructure Pressureless sintering Densification Mechanical properties

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In situ confined vertical growth of Co_(2.5)Ni_(0.5)Si_(2)O_(5)(OH)_(4)nanoarrays on rGO for an efficient oxygen evolution reaction

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Nano materials Science 2023年第4期5卷 351-360页

作者： Yang Mu Xiaoyu Pei Yunfeng Zhao Xueying Dong Zongkui Kou Miao Cui Changgong Meng Yifu Zhang State Key Laboratory of Fine Chemicals School of Chemical EngineeringDalian University of TechnologyDalian116024China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan430070China

Rational design of oxygen evolution reaction(OER)catalysts at low cost would greatly benefit the *** advantage of earth-abundant elements Si,Co and Ni,we produce a unique-structure where cobalt-nickel silicate hydroxide[Co_(2.5)Ni_(0.5)Si_(2)O_(5)(OH)_(4)]is vertically grown on a reduced graphene oxide(rGO)support(CNS@rGO).This is developed as a low-cost and prospective OER *** to cobalt or nickel silicate hydroxide@rGO(CS@rGO and NS@rGO,respectively)nanoarrays,the bimetal CNS@rGO nanoarray exhibits impressive OER performance with an overpotential of 307 mV@10 mA cm^(-2).This value is higher than that of CS@rGO and NS@*** CNS@rGO nanoarray has an overpotential of 446 mV@100 mA cm^(-2),about 1.4 times that of the commercial RuO_(2)*** achieved OER activity is superior to the state-of-the-art metal oxides/hydroxides and their *** vertically grown nanostructure and optimized metal-support electronic interactions play an indispensable role for OER performance improvement,including a fast electron transfer pathway,short proton/electron diffusion distance,more active metal centers,as well as optimized dualatomic electron *** advantage of interlay chemical regulation and the in-situ growth method,the advanced-structural CNS@rGO nanoarrays provide a new horizon to the rational and flexible design of efficient and promising OER electrocatalysts.

关键词： Co_(2.5)Ni_(0.5)Si_(2)O_(5)(OH)_(4)@rGO Vertical grown nanoarrays Geometric and electronic structure regulation Metal-support interactions Oxygen evolution reaction

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A room-temperature magnetic semiconductor from a Co-Fe-Nb-B metallic glass

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Science China(Physics,Mechanics & Astronomy) 2023年第4期66卷 94-99页

作者： Yu-Zhang Jiao Dmitry VLouzguine-Luzgin Ke-Fu Yao Zheng-Jun Zhang Na Chen Laboratory for Advanced Materials Processing Technology(MOE) State Key Laboratory of New Ceramics and Fine ProcessingSchool of Materials Science and EngineeringTsinghua UniversityBeijing 100084China Key Laboratory for Advanced Materials(MOE) Schoolof Materials Science and EngineeringTsinghua UniversityBeijing 100084China Advanced Institute for Materials Research(WPI-AIMR) Tohoku UniversitySendai 980-8577Japan Mathematics for Advanced Materials-OIL National Institute of Advanced Industrial Science and Technology(AIST)Sendai 980-8577Japan

Magnetic semiconductors with Curie temperatures higher than room temperature show potential for developing spintronic devices with combined data processing and storage functions for next-generation computing *** this study,we present an n-type Co_(19.8)Fe_(8.6)Nb_(4.3)B_(6.0)O_(61.3) magnetic semiconductor with a high Curie temperature of~559 *** magnetic semiconductor has a room-temperature resistivity of~2.10×10^(4)Ωcm and a saturation magnetization of~76 emu/cm^(3).The n-type Co_(19.8)Fe_(8.6)Nb_(4.3)B_(6.0)O_(61.3)magnetic semiconductor was deposited on p-type silicon to form a heterojunction,exhibiting a rectifying *** results provide the design principles for discovering high Curie temperature magnetic semiconductors with determined conduction types,which would play an essential role in realizing nonvolatile spin-based transistors that break free from the confines of currently established Si-based information technology.

关键词： magnetic semiconductor ferromagnetic metallic glass high Curie temperature

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The critical role of Zr in controlling the activity of Pd/Beta on the hydrogenation of phenol to cyclohexanone

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Chinese Journal of Chemical Engineering 2023年第5期57卷 79-87页

作者： Bin Gao Junwen Chen Qi Zuo Hongyan Wang Wenlin Li College of Chemical Engineering and Technology Taiyuan University of TechnologyTaiyuan 030024China State Key Laboratory of Catalytic Material and Reaction Engineering Research Institute of Petroleum ProcessingSinopecBeijing 100083China

The promoting effect of zirconium addition on Pd/Beta catalysts has been investigated in the selective hydrogenation of phenol to cyclohexanone in the aqueous phase. The activity of the catalyst in the reaction was greatly improved by introducing Zr atoms into the framework of H-Beta zeolite. An important synergy between the Zr species and Pd, affecting the Pd dispersion state on the support, has been observed. The modification of the support with Zr^(4+) improves the Lewis/Brφnsted acid ratio of the catalyst, suppressing the further transformation of cyclohexanone. The kinetics of Pd/Zr-Beta catalyst showed high selectivity to cyclohexanone. The catalytic results showed that the Pd/Zr-Beta had the best catalytic performance at the desired temperature of 80℃ for 5 h.

关键词： Palladium Phenol hydrogenation Cyclohexanone Zirconium Zeolite

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Localized in‑situ deposition:a new dimension to control in fabricating surface micro/nano structures via ultrafast laser ablation

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Frontiers of Optoelectronics 2023年第4期16卷 49-59页

作者： Peixun Fan Guochen Jiang Xinyu Hu Lizhong Wang Hongjun Zhang Minlin Zhong Laser Materials Processing Research Centre Key Laboratory for Advanced Materials Processing Technology(Ministry of Education)School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China

Controllable fabrication of surface micro/nano structures is the key to realizing surface functionalization for various *** a versatile approach,ultrafast laser ablation has been widely studied for surface micro/nano *** research eforts in this feld have been devoted to gaining more control over the fabrication processes to meet the increasing need for creation of complex *** this paper,we focus on the in-situ deposition process following the plasma formation under ultrafast laser *** an overview perspective,we frstly summarize the diferent roles that plasma plumes,from pulsed laser ablation of solids,play in diferent laser processing ***,the distinctive in-situ deposition process within surface micro/nano structuring is *** experimental work demonstrated that the in-situ deposition during ultrafast laser surface structuring can be controlled as a localized micro-additive process to pile up secondary ordered structures,through which a unique kind of hierarchical structure with fort-like bodies sitting on top of micro cone arrays were fabricated as a *** revealed laser-matter interaction mechanism can be inspiring for the development of new ultrafast laser fabrication approaches,adding a new dimension and more fexibility in controlling the fabrication of functional surface micro/nano structures.

关键词： Ultrafast laser ablation Laser micro/nanofabrication Surface micro/nano structures In-situ deposition Micro-additive fabrication

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Ablation resistance of ZrC coating modified by polymer-derived SiHfOC ceramic microspheres at ultrahigh temperature

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Journal of materials Science & technology 2024年第15期182卷 119-131页

作者： Xuemeng Zhang Yuyu Zhang Lingxiang Guo Bing Liu Yuqi Wang Hongbin Li Hejun Li Jia Sun Shaanxi Key Laboratory of Fiber Reinforced Light Composite Materials State Key Laboratory of Solidification ProcessingNorthwestern Polytechnical UniversityXi’an 710072China China Aerodynamics Research and Development Center Mianyang 621000China Science and Technology on Advanced Ceramic Fibers and Composites Laboratory National University of Defense TechnologyChangsha 410073China

Polymer-derived ceramics(PDCs)method opens up new possibilities for the preparation of novel multi-phase ceramic nanocomposites owing to the molecular design of the precursors at the nanoscale *** the current work,ZrC coatings incorporated with polymer-derived ceramic microspheres(CMS),SiH-fOC_CMS,were deposited to enhance the ablation resistance by supersonic atmosphere plasma *** 10.0 MW·m^(-2) plasma ablation at above 3000℃,the linear ablation rate of ZrC-SiHfOC_CMS coat-ing was reduced to 0.20μm·s^(-1),62%lower than that of the pristine ZrC *** improvement was ascribed to the presentence of viscous SiO_(2)/HfO_(2) molten mixed phase,rather than HfSiO4,which can ef-fectively seal pinholes and ***,the in-situ generated crystalline SiO_(2) had a lower oxygen diffusion rate than amorphous SiO_(2),meanwhile,m-HfO_(2) could improve the stability of SiO_(2) glassy film,thus further enhancing the ablation resistance.

关键词： ZrC Polymer-derived ceramics(PDCs) Carbon/Carbon composites Plasma spraying Plasma ablation

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Highly efficient and stable electrocatalyst for hydrogen evolution by molybdenum doped Ni-Co phosphide nanoneedles at high current density

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Nano Research 2024年第3期17卷 1066-1074页

作者： Chengyu Huang Zhonghong Xia Jing Wang Jing Zhang Chenfei Zhao Xingli Zou Shichun Mu Jiujun Zhang Xionggang Lu Hong Jin Fan Shengjuan Huo Yufeng Zhao College of Sciences&Institute for Sustainable Energy Shanghai UniversityShanghai 200444China State Key Laboratory of Metastable Materials Science and Technology Hebei Key Laboratory of Heavy Metal Deep-Remediation in Water and Resource ReuseYanshan UniversityQinhuangdao 066004China State Key Laboratory of Advanced Special Steel and Shanghai Key Laboratory of Advanced Ferrometallurgy School of Materials Science and EngineeringShanghai UniversityShanghai 200444China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China School of Physical and Mathematical Sciences Nanyang Technological UniversitySingapore639798

There is an increasingly urgent need to develop cost-effective electrocatalysts with high catalytic activity and stability as alternatives to the traditional Pt/C in catalysts in water *** this study,microspheres composed of Mo-doped NiCoP nanoneedles supported on nickel foam were prepared to address this *** results show that the nanoneedles provide sufficient active sites for efficient electron transfer;the small-sized effect and the micro-scale roughness enhance the entry of reactants and the release of hydrogen bubbles;the Mo doping effectively improves the electrocatalytic performance of NiCoP in alkaline *** catalyst exhibits low hydrogen evolution overpotentials of 38.5 and 217.5 mV at a current density of 10 mA·cm^(-2) and high current density of 500 mA·cm^(-2),respectively,and only 1.978 V is required to achieve a current density of 1000 mA·cm^(-2) for overall water *** functional theory(DFT)calculations show that the improved hydrogen evolution performance can be explained as a result of the Mo doping,which serves to reduce the interaction between NiCoP and intermediates,optimize the Gibbs free energy of hydrogen adsorption(△G_(*H)),and accelerate the desorption rate of **** study provides a promising solution to the ongoing challenge of designing efficient electrocatalysts for high-current-density hydrogen production.

关键词： transition metal phosphides Mo-doped NiCoP hydrogen evolution reaction gradient hydrothermal water splitting

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