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3D打印连续纤维增强树脂T型梁的弯曲性能

材料导报 2024年第7期38卷 242-248页

作者：吴思远单忠德陈恳刘丰刘晓军严春晖中国机械科学研究总院集团有限公司先进成形技术与装备国家重点实验室北京100048 清华大学机械工程系北京100084 南京航空航天大学机电学院南京210016

1中国机械科学研究总院集团有限公司先进成形技术与装备国家重点实验室,北京1000482清华大学机械工程系,北京1000843南京航空航天大学机电学院,南京210016实现基梁于结熔构融的沉轻积量技化、术功的能连化续设纤计维和增制强造树。脂本3... 详细信息

1中国机械科学研究总院集团有限公司先进成形技术与装备国家重点实验室,北京1000482清华大学机械工程系,北京1000843南京航空航天大学机电学院,南京210016实现基梁于结熔构融的沉轻积量技化、术功的能连化续设纤计维和增制强造树。脂本3D工作打对印筋工高艺0为m梁m结与构5的m制m造的提T供型了梁一打种印新件的在途不径,同该打工印艺参具数有下快的速弯近曲净性成能型进、行可测设计试性实强验,等研优究势了,能打够印基于熔融沉积技术的连续纤维增强树脂3D打印工艺为梁结构的制造提供了一种新的途径,该工艺具有快速近净成型、可设计性强等优势,能够实现梁结构的轻量化、功能化设计和制造。本工作对筋高0 mm与5 mm的T型梁打印件在不同打印参数下的弯曲性能进行测试实验,研究了打印厚度分别为0.7 mm、0.8 mm、0.9 mm时与打印丝束间距分别为0.6 mm、0.7 mm、0.8 mm时T型梁对应的弯曲强度与模量。由于3D打印连续纤维增强树脂材料存在着复杂的破坏模式,本研究运用声发射技术对T型梁的弯曲破坏过程进行测试分析,采用主成分分析法与K-means++聚类算法对采集的过程信号进行损伤分类。结果表明,当打印层厚为0.7~0.9 mm时,随着打印层厚的增加,T型梁的弯曲强度与模量均降低。当打印丝束间距为0.6~0.8 mm时,随着打印丝束间距的增加,T型梁的弯曲强度与模量降低。在T型梁从弯曲载荷加载初始到破坏失效阶段,对应特征信号可以聚类为五类,分别对应五种破坏模式,即基体开裂、层间剥离、纤维与基体脱粘、纤维开裂及纤维断裂,分类结果能够很好地解释弯曲破坏过程。

关键词： 3D打印 T型梁弯曲性能声发射主成分分析 K-means++

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镍锌铁氧体吸波材料研究进展

宇航材料工艺 2024年第1期54卷 29-35页

作者：谭春林李宇东陈肯刘墨轩湖南航天磁电有限责任公司长沙410299

综述了镍锌铁氧体吸波材料的研究情况。从磁性能、配方对吸波性能的影响,以及与其他材料复合对吸波性能的影响等方面,对镍锌铁氧体吸波材料进行比较全面的总结,并与我司研究情况进行对比,希望对镍锌铁氧体吸波材料的开发与应用提供支持。

关键词：镍锌铁氧体吸波材料

Local charge neutrality condition,Fermi level and majority carrier density of a semiconductor with multiple localized multi-level intrinsic/impurity defects

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Journal of Semiconductors 2011年第11期32卷 1-8页

作者： ken K.Chin Department of Physics and Apollo CdTe Solar Energy Research Center New Jersey Institute of Technology Department of Photonic and Information Engineering School of Electronic and Information EngineeringBeihang University

For semiconductors with localized intrinsic/impurity defects, intentionally doped or unintentionally incorporated, that have multiple transition energy levels among charge states, the general formulation of the local charge neutrality condition is given for the determination of the Fermi level and the majority carrier density. A graphical method is used to illustrate the solution of the problem. Relations among the transition energy levels of the multi-level defect are derived using the graphical method. Numerical examples are given for p-doping of the CdTe thin film used in solar panels and semi-insulating Si to illustrate the relevance and importance of the issues discussed in this work.

关键词： multi-level defects defect complex intrinsic impurity semiconductor Fermi level majority carrier density

Structure and Mechanical Behavior of Cellulose Nanofiber and Micro-Fibrils by Molecular Dynamics Simulation

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Soft Nanoscience Letters 2013年第3期3卷 58-67页

作者： ken-ichi Saitoh Haruhiko Ohno Syunichiro matsuo Department of Mechanical Engineering Faculty of Engineering Science Kansai University Suita Japan KYOCERA Corporation Kyoto Japan.

Cellulose nanofiber (CNF) and CNF micro-fibrils (CNF-MFs) are computationally modeled by molecular dynamics with united atom (UA) methodology of polymers. Structural stability and mechanical properties of these materials are focused on. Diffusion coefficient decreases with increase of the number of shells in CNF-MF. The structure of CNF-MFs with crystalline alignment is totally stabilized with twist which is an accumulation of torsion angles at Glycosidic bonds between monomers inside CNFs. Unique fiber drawing simulation, where a single CNF fiber is taken out of CNF-MF structure, is first conducted. The CNF fiber which is drawn out stretches up to relatively large strain, with linear increase of tensile stress. The computation results show that, the larger the number of shell structure of CNF-MF is, the larger the stretch and the stress of drawn fibers are.

关键词： Cellulose Nanofiber Molecular Dynamics Wiredrawing Mechanical Properties Biomaterial Twist Angle

Approximate graphical method of solving Fermi level and majority carrier density of semiconductors with multiple donors and multiple acceptors

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Journal of Semiconductors 2011年第6期32卷 1-6页

作者： ken K.Chin Department of Physics and Apollo CdTe Solar Energy Research Center New Jersey Institute of Technology

We present a generic approximate graphical method for determining the equilibrium Fermi level and majority carrier density of a semiconductor with multiple donors and multiple acceptors compensating each other. Simple and easy-to-follow procedures of the graphical method are *** graphically plotting two wrapping step functions facing each other,one for the positive hole-ionized donor and one for the negative electron-ionized acceptor,we have the crossing point that renders the Fermi level and majority carrier *** the graphical method,new equations are derived,such as the carrier compensation proportional to N;/N;,not the widely quoted N;-N;.Visual insight is offered to view not only the result of graphic determination of Fermi level and majority carrier density but also the dominant and critical pair of donors and acceptors in *** graphical method presented in this work will help to guide the design,adjustment,and improvement of the multiply doped *** of this approximate graphical method with previous work on compensation,and with some experimental results,is *** work in the field is proposed.

关键词： doping compensation Fermi level carrier density graphical method ionization

The Structure and Mechanical Properties of Cr4Mo4V Steel Treated by PIII Carbonitriding

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稀有金属材料与工程 2012年第S1期41卷 176-179页

作者： ken Yukimura Harbin Institute of Technology Harbin 150001China

The composition and structure of PIII(plasma immersion ion implantation)carbonitrided Cr4Mo4V steel were analyzed using X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD),optical microscopy(OM)and *** results indicate that the nitride and carbide are dispersion phase precipitation and except formation of compound other implantation atoms dissolve into martensite *** total concentration of carbon and nitrogen is about 30 at%near the surface,and still keeps at about 20 at%even at the depth of 8μ*** effect of treatment temperature,implantation time and ratio of N2 to CH4 on the hardness and wear resistance of carbonitrided layer are *** is found that the hardness of Cr4Mo4V steel increases after *** highest hardness of samples is 22.3 GPa,which is about 1.8 times than initial *** dry-wear resistance of the samples is also improved after treatment,and the sample with higher hardness shows the better wear resistance.

关键词： Cr4Mo4V steel PBII carbonitriding hardness wear resistance

Role of STAT3 in inflammatory bowel disease

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World Journal of Gastroenterology 2008年第33期14卷 5110-5114页

作者： ken Sugimoto Experimental Pathology Massachusetts General Hospital Harvard Medical SchoolBoston MA 02114 United States

Signal transducers and activators of transcription 3 (STAT3) play an important role in various autoimmune disorders including inflammatory bowel disease (IBD). Recent studies have revealed that STAT3 activation plays distinctly different roles between innate immune responses and acquired immune responses in colitis. STAT3-mediated activation of acquired immune re-sponses plays a pathogenic role in colitis by enhancing the survival of pathogenic T cells. In contrast, STAT3-mediated activation of innate responses contributes to the suppression of colitis. This review will summarize the current understanding of the roles of STAT3 in IBD and the potential of targeting STAT3 for the treatment of IBD, emphasizing recent observations.

关键词： Inflammatory bowel disease STAT3 Inflammation Innate immunity Acquired immunity

Analysis of the stress wave and rarefaction wave produced by hypervelocity impact of sphere onto thin plate

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Defence Technology（防务技术） 2020年第5期16卷 969-979页

作者： ken Wen Xiao-wei Chen State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081China Institute of Systems Engineering China Academy of Engineering PhysicsMianyangSichuan621999China Advanced Research Institute of Multidisciplinary Science Beijing Institute of TechnologyBeijing100081China

Shock wave is emitted into the plate and sphere when a sphere hypervelocity impacts onto a thin *** fragmentation and phase change of the material caused by the propagation and unloading of shock wave could result in the formation of debris cloud *** models are deduced based on one-dimensional shock wave theory and the geometry of sphere,which uses elliptic equations(corresponding to ellipsoid equations in physical space)to describe the propagation of shock wave and the rarefaction ***“Effective thickness”is defined as the critical plate thickness that ensures the rarefaction wave overtake the shock wave at the back of the ***“Effective thickness”is directly related to the form of the debris *** relation of the“Effective thickness”and the“Optimum thickness”is also *** impacts of Al spheres onto Al plates are simulated within SPH to verify the propagation models and associated *** results show that the wave fronts predicted by the propagation models are closer to the simulation result at higher impact *** curvatures of the wave fronts decrease with the increase of impact *** predicted“Effective thickness”is consistent with the simulation *** analysis about the shock wave propagation and unloading in this paper can provide a new sight and inspiration for the quantitative study of hypervelocity impact and space debris protection.

关键词： Hypervelocity impact Debris cloud Shock wave Rarefaction wave Effective thickness of plate

Emissivity of La_(1-x)Sr_xMnO_3/acrylic Resin Thermal Control Coating

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稀有金属材料与工程 2012年第S1期41卷 253-255页

作者： Yukimura ken Harbin Institute of Technology Harbin 150001China

Thermal control coatings were fabricated by mixing of La1-xSrxMnO3(LSMO)powder and acrylic resin and brushed on Al alloy *** powders of La0.7Sr0.3MnO3 and La0.8Sr0.2MnO3 were prepared using sol-gel *** results reveal the phase structure of LSMO powders are *** transition temperature from metal to insulator of La0.7Sr0.3MnO3 and La0.8Sr0.2MnO3 are 300 and 275 K,*** emissivity evolution with temperature of the coatings was *** La0.7Sr0.3MnO3/acrylic resin coating,the emissivity increases from 0.56 to 0.88,and for La0.7Sr0.3MnO3/acrylic resin coating from 0.50 to 0.90.

关键词： thermal control coatings LSMO emissivity