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Efficient cutting path planning for a non-spherical tool based on an iso-scallop height distance field

Chinese Journal of Aeronautics 2024年第7期37卷 496-510页

作者： Jiancheng HAO Dong HE Zhaoyu LI Pengcheng hu Yuanzhi chen Kai TANG Department of Mechanical and Aerospace Engineering Hong Kong University of Science and TechnologyHong Kong 999077China The Hong Kong University of Science and Technology(Guangzhou) Smart Manufacturing ThrustNanshaGuangzhou 511400China HKUST Shenzhen-Hong Kong Collaborative Innovation Research Institute Shenzhen 518057China HKUST Shenzhen Research Institute Shenzhen 518057China

Iso-scallop height machining means,when machining a freeform surface,the scallop height between any two neighboring tool paths on the surface will be a constant(i.e.,the given threshold),which is preferable among various freeform surface machining strategies due to its high machining efficiency as well as better machine tool’s ***,all the existing iso-scallop height path planning methods pertain to only the ball-end or flat-end types of *** recent years,the non-spherical cutting tool has become more and more popular,especially for five-axis machining of complex freeform surfaces,majorly owing to its non-constant curvature which can be utilized to adaptively fit the tool to the surface to both avoid the local gouging and enlarge the cutting ***,there have been no reported works on iso-scallop height five-axis tool path generation for a non-spherical tool,and,in this paper,we present ***,we first define and construct two fields on the surface to be machined-the collision-free tool orientation field(vector)and the iso-scallop height distance field(scalar).The iso-lines of the scalar field and their associated tool orientation field vectors then naturally serve as potential iso-scallop height five-axis tool paths,and we present a propagation-based algorithm to construct the desired tool path from the *** computer simulation and physical cutting experiments confirm that everywhere on the surface,except maybe near the saddle curves of the scalar filed,the scallop height is exactly the given *** adding the saddle curves as extra tool paths,the final machined surface then is assured of the required scallop height requirement.

关键词： Freeform surface machining Iso-scallop tool path Customized tool Five-axis tool path Computer aided manufacturing

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Adaptive observer-based integral event-triggered antivibration control of a full aircraft active landing gear system with irregular runway excitations

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Science China(Information Sciences) 2024年第6期67卷 248-261页

作者： Wenxiao hu chenglong DU Fanbiao LI Xinmin chen Chunhua YANG Weihua GUI School of Automation Central South University Research Center in System Engineering for Special Aircrafts Ningbo Institute of Materials Technology and EngineeringChinese Academy of Sciences

This study addresses the antivibration issue of a full aircraft active landing gear system(LGS)under landing impact and runway excitations via a novel adaptive observer-based integral event-triggered control method. First, a full aircraft active LGS comprising a front gear and two synchronized main left and right gears with active suspensions is established, where the information exchange among them is not implemented directly. Second, two adaptive observers are designed separately for the front and main LGSs to identify the varying damping parameters and estimate the system states simultaneously. Third, estimated states are transmitted to a shared network through a novel integral event-triggered mechanism(I-ETM);thus, the front and main LGSs are interconnected, and a networked control scheme for the aircraft LGS is constructed. Additionally, the integrated active control law is designed with the aid of the transmitted states of the front and main LGSs, enhancing the robustness against the pitch vibration of the ***, the L2-stability of the hybrid system is guaranteed to depress the vertical vibration effect of the landing impact and irregular runway excitations, thus improving passenger safety and comfort. Moreover,a codesign method is provided to obtain feasible solutions to the gain matrices of the observers and controllers simultaneously. Simulation and comparison results are presented to illustrate the effectiveness and superiority of the proposed control scheme in antivibration and saving communication resources.

关键词： aircraft active landing gear antivibration control integral event-triggered mechanism adaptive observer ${\mathcal{L}}_2$-stability

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Synergically regulated silver species and surface oxygen on manganese oxide for promoted activity of formaldehyde oxidation

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Journal of Environmental Sciences 2024年第4期138卷 709-718页

作者： Shuo hu Jianghao Zhang Xueyan chen Xiaoxiao Qin Jinshui Yao Changbin Zhang School of Materials Science&Engineering Qilu University of Technology(Shandong Academy of Sciences)Jinan 250353China State Key Joint Laboratory of Environment Simulation and Pollution Control Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China University of Chinese Academy of Sciences Beijing 100049China

Formaldehyde(HCHO)is a common indoor pollutant that is detrimental to human *** efficient removal has become an urgent demand to reduce the public health *** this work,Ag-MnO_(x)-based catalysts were prepared and activated under different atmosphere(i.e.,air,hydrogen(H_(2))and carbon monoxide(CO))for efficient oxidation of *** catalyst activated with CO(Ag/Mn-CO)displayed the highest activity among the tested samples with 90% conversion at 100℃ under a gas space velocity of 75,000 mL/(g_(cat)·hr).Complementary characterizations demonstrate that CO reduction treatment resulted in synergically regulated content of surface oxygen on support to adsorb/activate HCHO and size of Ag particle to dissociate oxygen to oxidize the adsorbed *** contrast,other catalysts lack for either abundant surface oxygen species or metallic silver with the appropriate particle size,so that the integrate activity is limited by one specific reaction *** study contributes to elucidating the mechanisms regulating the oxidation activity of Ag-based catalysts.

关键词： HCHO oxidation Ag-MnO_(x)-based catalyst Activation condition Synergic regulation Surface oxygen Oxidized Ag

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Presence of a long nuclear-localization signal sequence in homeodomain transcription factor Nkx 1.2

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Journal of Oceanology and Limnology 2024年第2期42卷 620-626页

作者： Xinyi LI Lihui chen Xinyuan WANG chen SUN Guangdong JI Guobin hu Zhenhui LIU College of Marine Life Science and Institute of Evolution&Marine Biodiversity Ocean University of ChinaQingdao 266003China Laoshan Laboratory Qingdao 266237China

Homeodomains,a 60-amino acid sequence encoded by 180 nucleotides,are highly conserved DNA-binding motifs that are present in a variety of transcription factors in species ranging from yeast to *** NKX proteins belong to the homeodomain(HD)-containing transcription factor *** play vital roles in the regulation of ***1-2 is one member of the NKX *** present,information about its nuclear localization signal(NLS)sequence is *** studied the NLS sequence of zebrafish Nkx1.2 by introducing sequence changes such as deletion,mutation,and truncation,and identified an NLS motif(QNRRTKWKKQ)that is localized at the C-terminus of the ***,the deletion of two amino acid residues(RR)in this NLS motif prevents Nkx1.2 from entering the nucleus,indicating that the two amino acids are essential for Nkx1.2 nuclear ***,the NLS motif alone is unable to target cytoplasmic protein glutathione S-transferase(GST)to the *** intact homeodomain is necessary for mediating the complete nuclear transport of cytoplasmic *** most nuclear import proteins with short NLS sequences,a long NLS is present in zebrafish *** also demonstrated that the sequences of homeodomain of NKX1.2 are well conserved among different *** study is informative to verify the function of the NKX1.2 protein.

关键词： NKX1.2 NKX protein homeodomain nuclear localization signal(NLS) nuclear transport

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Controllable large-scale processing of temperature regulating sheath-core fibers with high-enthalpy for thermal management

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Nano Materials Science 2024年第3期6卷 337-344页

作者： Ziye chen Zexu hu Shining chen Senlong Yu Liping Zhu Hengxue Xiang Meifang Zhu Key Laboratory for Modification of Chemical Fibers and Polymer Materials College of Materials Science and EngineeringDonghua UniversityShanghai201620China College of Mechanical and Engineering Donghua UniversityShanghai201620China

Temperature regulating fibers(TRF_(s)) with high enthalpy and high form stability are the key factors for thermal management. However, the enthalpies of most TRFsare not high, and the preparation methods are still at the laboratory scale. It remains a great challenge to use industrial spinning equipment to achieve continuous processing of TRF_(s) with excellent thermal and mechanical properties. Here, polyamide 6(PA6) based TRF_(s) with a sheath-core structure were prepared by bicomponent melt-spinning. The sheath-core TRF(TRF_(sc)) are composed of PA6 as sheath and functional PA6 as core, which are filled with the shape stable phase change materials(ssPCM),dendritic silica@polyethylene glycol(SiO_(2)@PEG). With the aid of the sheath structure, the filling content of SiO_(2)@PEG can reach 30 %, so that the enthalpy of the TRF_(s) can be as high as 21.3 J/g. The ultra-high enthalpy guarantees the temperature regulation ability during the alternating process of cooling and heating. In hot environment, the temperature regulation time is 6.59 min, and the temperature difference is 12.93℃. In addition, the mechanical strength of the prepared TRF_(sc) reaches 2.26 cN/dtex, which can fully meet its application in the field of thermal management textiles and devices to manage the temperature regulation of the human body or precision equipment, etc.

关键词： Thermal management Hybrid fibers Polyamides Bicomponent melt spinning Temperature regulating fibers

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Transient flameout process of boron-magnesium agglomerates during combustion in oxygen-rich atmospheres

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Particuology 2024年第5期88卷 290-301页

作者： Lian Duan Zhixun Xia Yunchao Feng Binbin chen Likun Ma Jianxin hu College of Aerospace Science and Engineering National University of Defense TechnologyChangsha 410073China School of Mechanical Engineering and Mechanics Xiangtan UniversityXiangtan 411105China

In this study,boron–magnesium agglomerates with varying mass ratios were prepared by drying a micron-sized boron–magnesium mixed suspension,and the combustion process of these agglomerates under different oxygen-rich concentrations were investigated using a laser ignition *** test results showed that when the mass fraction of magnesium powder in boron-magnesium agglomerates exceeded a certain threshold(between 2%and 5%),flame extinction and reignition occurred after a significant reduction in the agglomerate volume during *** process is referred to as the transient flameout process,which is affected by the magnesium content of the agglomerate and the oxygen concentration in the ambient *** increase in the magnesium content or oxygen concentration makes this phenomenon more *** weakening of the flame intensity,a dark film gradually covered the particle surfaces.X-ray diffraction and elemental analyses of the cross-section and outer surface of the condensed combustion product suggested that the dark film is primarily composed of Mg-B-O ternary *** film prevents direct contact between boron and oxygen,thereby inhibiting surface and gas-phase reactions and leading to the occurrence of the transient flameout phenomenon.

关键词： Agglomerated particle Boron–magnesium fuel Boron combustion Transient flameout process Solid fuel ramjet

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Space truss construction modeling based on on-orbit assembly motion feature

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Chinese Journal of Aeronautics 2024年第3期37卷 365-379页

作者： Changjie ZHAO Weizhong GUO Meng chen Jiaxing hu Youcheng HAN Rongfu LIN State Key Lab of Mechanical System and Vibration Shanghai Jiao Tong UniversityShanghai 200240China Institute of Aerospace System Engineering Shanghai Shanghai 201109China

More space truss construction has been planned to develop and utilize space *** trusses are designed in the way of large-scale,complex,modular,and on-orbit *** meet the upcoming challenge of large-scale space infrastructure construction,it is necessary to study space truss automation design and robotic *** paper proposes an ordinal finite screw adjacency matrix model(OFSAMM),focusing on the relationship between assembly motions,to express and compute a space truss *** this model,a space truss is abstracted as a set of ordered assembly motions,each of which is recorded as a finite screw as the basic element of the truss and its *** operation of truss transformation is also derived under this ***,the truss configuration,the assembly sequence,the truss sub-assembly,the truss components,and the on-orbit assembly task can be expressed and calculated in a unified model,which is calculated and stores the truss topology and assembly with the minimum storage *** the end of this paper,we introduce how to synthesize and optimize space truss design through two *** study will help to improve design ***,it provides a theoretical basis for the automatic construction of space truss structures,especially in the next stage.

关键词： Adjacency matrix Finite screw On-orbit construction modeling Space applications Space trusses Topology design

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A low-cost and high-strength basalt/carbon fiber reinforced polymer improved by imitating tree-root micro/nano aramid short fiber

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Chinese Journal of Aeronautics 2024年第10期37卷 526-538页

作者： Guangming YANG Yanan LYU Fei chenG Jiaxin HE Shihao ZUO Wenyi huANG Yunsen hu Xiaozhi hu Xi chen Shock and Vibration of Engineering Materials and Structures Key Lab of Sichuan Province Southwest University of Science and TechnologyMianyang 621010China Engineering Research Center of Biomass Materials Ministry of EducationSouthwest University of Science and TechnologyMianyang 621010China School of Materials and Chemistry Southwest University of Science and TechnologyMianyang 621010China Institute of Automation Chinese Academy of SciencesBeijing 100190China School of Artificial Intelligence University of Chinese Academy of SciencesBeijing 100101China School of Mechanical Engineering Jiangsu University of Science and TechnologyZhenjiang 212003China Department of Mechanical Engineering University of Western AustraliaPerth 6009Australia

The high-strength Basalt Carbon Fiber Reinforced Polymer(BCFRP)composites had been manufactured by guiding Imitating Tree-root Micro/Nano Aramid Short Fiber(ITMNASF)into the interlayer of Basalt Fiber(BF)and Carbon Fiber(CF)plies to form thin interleaving,and various mass proportions of IT-MNASF were designed to discuss the reinforcing effect on the BCFRP heterogeneous *** results of three points bending tests showed that flexural strength and energy absorption of 4wt%IT-MNASF reinforced BCFRP heterogeneous composites had been improved by 32.4%and 134.4%respectively compared with that of unreinforced *** 4wt%IT-MNASF reinforced BCFRP specimens showed both a greater strength and a lower cost(reduced by 31%around)than that of plain CFRP composites.X-ray micro-computed tomography scanning results exhibited that the delamination-dominated failure of plain BCFRP composites was changed into multi-layer BF and CF fabrics *** reinforcing mechanism revealed that the introduced IT-MNASF could construct quasi-vertical fiber bridging,and it was used as"mechanical claws"to grasp adjacent fiber layers for creating a stronger mechanical interlocking,and this effectively improved resin-rich region and interfacial transition region at the *** simple and effective IT-MNASF interleaving technique was very successful in low-cost and high-strength development of BCFRP heterogeneous composites.

关键词： Basalt carbon fiber reinforced polymer Micro/nano aramid fiber Fiber bridging Strength improvement Low-cost substitution

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Accelerating solar driven CO_(2) reduction via sulfur-doping boosted water dissociation and proton transfer

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Nano Research 2024年第3期17卷 1056-1065页

作者： Ke Yan Liang chen Yangguang hu Ting Wang Cong chen Chao Gao Youju huang Benxia Li School of Chemistry and Chemical Engineering Key Laboratory of Surface&Interface Science of Polymer Materials of Zhejiang ProvinceZhejiang Sci-Tech UniversityHangzhou 310018China College of Material Chemistry and Chemical EngineeringKey Laboratory of Organosilicon Chemistry and Material TechnologyMinistry of EducationHangzhou Normal UniversityHangzhou 311121China School of Chemistry and Materials Science University of Science and Technology of ChinaHefei 230026China

Exploring efficient photocatalysts for solar driven CO_(2) reduction with water(H_(2)O)as a proton donor is highly imperative but remains a great challenge because the synchronous enhancement of CO_(2) activation,H_(2)O dissociation and proton transfer is hardly achieved on a ***,the sluggish H_(2)O dissociation impedes the photocatalytic CO_(2) reduction reaction involving multiple proton–electron coupling transfer ***,a sulfur-doped BiOCl(S-BiOCl)photocatalyst with abundant oxygen vacancies(OV)is developed,which exhibits broadband-light harvesting across solar spectrum and distinct photothermal effect due to *** photocatalytic CO_(2) reduction with H_(2)O in a gas–solid system,the high CO yield of 49.76μmol·g_(cat)^(-1)·h^(-1) with 100%selectivity is achieved over the S-BiOCl catalyst under a simulated *** H_(2)O-assisted CO_(2) reduction reaction on S-BiOCl catalyst is triggered by photocatalysis and the photothermal heating further enhances the reaction *** kinetic isotope experiments indicate that the sluggish H_(2)O dissociation affects the whole photocatalytic CO_(2) reduction *** presence of oxygen vacancies promotes the adsorption and activation of H_(2)O and CO_(2),and the doped S sites play a crucial role in boosting H_(2)O dissociation and accelerating the dynamic migration of hydrogen *** a result,the ingenious integration of OV defects,S sites and photothermal effect in S-BiOCl catalyst conjointly contributes to the significant improvement in photocatalytic CO_(2) reduction performance.

关键词： BiOCl sulfur doping photocatalytic CO_(2)reduction H_(2)O activation proton feeding

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Effect of Y substitution on the microstructure,magneto-optical,and thermal properties of(Tb_(1−x)Y_(x))_(3)Al_(5)O_(12)transparent ceramics

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Journal of Advanced Ceramics 2024年第4期13卷 529-538页

作者： Lixuan Zhang Dianjun hu Xiao Li Ziyu Liu chen hu Lexiang Wu Tingsong Li Dariusz Hreniak Jiang Li Transparent Ceramics Research Center Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 201899China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China Ganjiang Innovation Academy Chinese Academy of SciencesGanzhou 341000China Institute of Low Temperature and Structure Research Polish Academy of SciencesWroclaw 50-422Poland

Faraday isolators can prevent the front-end system from disturbance and damage caused by a back-reflected beam,so they are important elements in laser *** magneto-optical materials are the most important component in Faraday isolators,the studies on magneto-optical materials have attracted much attention these ***_(3)Al_(5)O_(12)(TAG)ceramics are considered to be one of the most promising magneto-optical materials for visible to near-infrared wavelength band application because of their outstanding comprehensive magneto-optical ***,the optical quality of TAG ceramics needs further optimization to meet the application *** this work,high optical quality(Tb_(1−x)Y_(x))_(3)Al_(5)O_(12)(x=0,0.05,0.1,0.2,and 0.3)magneto-optical ceramics were fabricated successfully by solid-state reaction sintering combined with hot isostatic pressing(HIP)*** the ceramics obtained showed a single garnet phase for different values of x in the range *** addition of Y_(2)O_(3) was found to suppress the secondary phase and improve optical quality *** ceramic samples obtained had clear grain boundaries and possessed the in-line transmittance values of 82.9%at 1064 nm and 82.2%at 633 nm,*** Verdet constants of(Tb_(1−x)Y_(x))_(3)Al_(5)O_(12)ceramics with x=0,0.05,0.1,0.2,and 0.3 were−188.1,−175.4,−168.5,−143.0,and−119.9 rad/(T·m),*** thermal conductivity of TAG ceramics was found to be 5.23 W/(m·K)at 25℃,and when 20%Y was substituted in place of Tb,the thermal conductivity decreased by only 9.4%.

关键词： (Tb_(1−x)Y_(x))_(3)Al_(5)O_(12)ceramics magneto-optical materials optical quality thermal properties

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