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Preparation and mechanical properties of c/c composites reinforced with arrayed Sic columnar pins

cERAMIcS INTERNATIONAL 2021年第17期47卷 24262-24269页

作者： Jia, Jiangang Ju, Jiakang Liu, Shunwei Ji, Genshun State Key Lab Adv Proc & Recycling Nonferrous Met Lanzhou Peoples R China Lanzhou Univ Technol Sch Mat Sci & Engn Lanzhou 730050 Peoples R China

c/c composites with Sic columnar pins were fabricated by a recently developed space-holder method. Effects of Sic columnar pins with pins-row spacing of 5 mm and 4 mm on mechanical properties and toughening of c/c composites were characterized and discussed. corresponding porous c/c composite matrices were also characterized. The results show that introduction of Sic columnar pins not only improves the compressive and shear properties of c/c composites, but significantly affects the Pyc texture of the c/c composite matrix. Under identical TG-cVI deposition conditions, the pristine c/c composites (S0), the unidirectional porous c/c composites (S1 and S2), and the c/c composites with Sic columnar pins (S3 and S4) show typical low-textured Pyc, high-textured Pyc, and medium-textured Pyc, respectively. The mechanical properties of unidirectional porous c/c composites with channels-row spacing of 5 mm (S1) are higher than those of unidirectional porous c/c composites with channels-row spacing of 4 mm (S2). conversely, for the c/c composites with Sic columnar pins, the mechanical properties of samples with columns-row spacing of 5 mm (S3) are lower than those with columnsrow spacing of 4 mm (S4). Moreover, the compressive strength P//(load direction parallel to the channel), P perpendicular to (load direction vertical to the channel), and shear strength of S3 and S4 is respectively higher than that of S1. Therefore, introduction of Sic columnar pins can effectively improve the mechanical properties of composites without significantly changing the density.

关键词： c c composites Sic columnar pins Shear strength compressive strength

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DEcARBURIZATION OF FE-cR-c STEELS DURING HIGH-TEMPERATURE OXIDATION

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OXIDATION OF METALS 1988年第5-6期29卷 419-433页

作者： HAJDUGA, M KUcERA, J CZECHOSLOVAK ACAD SCI INST PHYS METCS-61662 BRNOCZECHOSLOVAKIA

Isothermal oxidation treatments were carried out on Fe-cr-c steels. The steels containing 0.08, 0.15, 0.17, 0.88, 1.51, and 12.77wt.% cr and 0.10, 0.49, 1.19, 0.18, 1.05, and 1.63 wt.% c were oxidized in ambient air at temperatures of 900, 1000, and 1200°c. Steels containing 13.22, 12.90, 12.52, and 12.77wt.% cr and 0.15, 0.30, 0.50, and 1.63 wt.% c were heated (1100°c/3hr) in a flowing atmosphere of O_class="a-plus-plus">2-N_{class="a-plus-plus">2}-He in a SETARAM thermobalance. Evidence of decarburization of the steels is given by metallographic observations, by direct measurements of carbon diffusivities from the decarburization profiles in the oxidized samples, and by the results of kinetics measurements.^{class="a-plus-plus">3} carbon diffusion coefficients were measured by the standard sectioning method in the samples oxidized in air. A. generalized equation for carbon diffusivity in Fe-cr-c alloys is developed in terms of N_{class="a-plus-plus">cr}[wt.%], N_{class="a-plus-plus">c}[wt.%], and T[K].

关键词： Oxidation decarburization carbon diffusivity effect of oxidation atmosphere Fe cr c

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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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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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Load-carrying capacity of Wc/c-coated gears lubricated with a low-viscosity oil

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LUBRIcATION ScIENcE 2016年第3期28卷 127-139页

作者： Krzan, Boris Univ Ljubljana Fac Mech Engn Ljubljana 61000 Slovenia

The application of low-friction coatings on the surfaces of gear teeth is primarily motivated by the increasing demands for load-carrying capacity or the rolling-contact fatigue life. Despite the costs of manufacturing being higher, better performance is an important consideration for many demanding applications. In the present study, we have investigated the load-carrying capacity of Wc/c-coated gears that were lubricated with an oil blend that was formulated in-house. A significantly higher load-carrying capacity was found for the Wc/c-coated gears lubricated with a tailored, low-viscosity oil in comparison with the case-carburised gears lubricated with a conventional gear oil of a similar viscosity. The carburised gears failed due to scuffing on the pinion tip, while coating thinning on the pinion face and coating fracture in the wheel-root area are the dominant failure mechanisms for Wc/c-coated gears. An approximately 40% lower roughness was found on the coated gear flanks. copyright (c) 2015 John Wiley & Sons, Ltd.

关键词： gears Wc c lubrication load-carrying capacity surface roughness

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The factor H variant associated with age-related macular degeneration (His-384) and the non-disease-associated form bind differentially to c-reactive protein, fibromodulin, DNA, and necrotic cells

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JOURNAL OF BIOLOGIcAL cHEMISTRY 2007年第15期282卷 10894-10900页

作者： Sjoberg, Andreas P. Trouw, Leendert A. clark, Simon J. Sjolander, Jonatan Heinegard, Dick Sim, Robert B. Day, Anthony J. Blom, Anna M. Lund Univ Dept Lab Med Sect Med Prot Chem Malmo Univ Hosp S-20502 Malmo Sweden Univ Oxford Dept Biochem MRC Immunochem Unit Oxford OX1 3QU England Lund Univ Dept Expt Med Sci S-22184 Lund Sweden Univ Manchester Fac Life Sci Manchester M13 9PT Lancs England

Recently, a polymorphism in the complement regulator factor H (FH) gene has been associated with age-related macular degeneration. When histidine instead of tyrosine is present at position 384 in the seventh complement control protein (ccP) domain of FH, the risk for age-related macular degeneration is increased. It was recently shown that these allotypic variants of FH, in the context of a recombinant construct corresponding to ccPs 6 - 8, recognize polyanionic structures differently, which may lead to altered regulation of the alternative pathway of complement. We show now that His-384, corresponding to the risk allele, binds c-reactive protein (cRP) poorly compared with the Tyr-384 form. We also found that c1q and phosphorylcholine do not compete with FH for binding to c-reactive protein. The interaction with extracellular matrix protein fibromodulin, which we now show to be mediated, at least in part, by ccP6 - 8 of FH, occurs via the polypeptide of fibromodulin and not through its glycosaminoglycan modifications. The Tyr-384 variant of FH bound fibromodulin better than the His-384 form. Furthermore, we find that ccP6 - 8 is able to interact with DNA and necrotic cells, but in contrast the His-384 allotype binds these ligands more strongly than the Tyr-384 variant. The variations in binding affinity of the two alleles indicate that complement activation and local inflammation in response to different targets will differ between His/His and Tyr/Tyr homozygotes.

关键词： c-Reactive Protein complement Factor H DNA Extracellular Matrix Proteins c

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Electrochemical Activation of Li2MnO3 Electrodes at 0 °c and Its Impact on the Subsequent Performance at Higher Temperatures

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MATERIALS 2020年第19期13卷 4388页

作者： Susai, Francis Amalraj Talianker, Michael Liu, Jing Rosy Paul, Tanmoy Grinblat, Yehudit Erickson, Evan Noked, Malachi Burstein, Larisa Frenkel, Anatoly I. Tsur, Yoed Markovsky, Boris Aurbach, Doron Bar Ilan Univ Dept Chem IL-52900 Ramat Gan Israel Bar Ilan Univ Inst Nanotechnol & Adv Mat IL-52900 Ramat Gan Israel Ben Gurion Univ Negev Dept Mat Engn IL-84105 Beer Sheva Israel Manhattan Coll Dept Phys New York NY 10471 USA Technion Israel Inst Technol Dept Chem Engn IL-3200003 Haifa Israel Technion Israel Inst Technol Grand Technion Energy Program IL-3200003 Haifa Israel Tel Aviv Univ Wolfson Appl Mat Res Ctr IL-69978 Tel Aviv Israel SUNY Stony Brook Dept Mat Sci & Chem Engn Stony Brook NY 11794 USA

This work continues our systematic study of Li- and Mn- rich cathodes for lithium-ion batteries. We chose Li2MnO3 as a model electrode material with the aim of correlating the improved electrochemical characteristics of these cathodes initially activated at 0 degrees c with the structural evolution of Li2MnO3, oxygen loss, formation of per-oxo like species (O-2(2-)) and the surface chemistry. It was established that performing a few initial charge/discharge (activation) cycles of Li2MnO3 at 0 degrees c resulted in increased discharge capacity and higher capacity retention, and decreased and substantially stabilized the voltage hysteresis upon subsequent cycling at 30 degrees c or at 45 degrees c. In contrast to the activation of Li2MnO3 at these higher temperatures, Li2MnO3 underwent step-by-step activation at 0 degrees c, providing a stepwise traversing of the voltage plateau at >4.5 V during initial cycling. Importantly, these findings agree well with our previous studies on the activation at 0 degrees c of 0.35Li(2)MnO(3)center dot 0.65Li[Mn0.45Ni0.35co0.20]O-2 materials. The stability of the interface developed at 0 degrees c can be ascribed to the reduced interactions of the per-oxo-like species formed and the oxygen released from Li2MnO3 with solvents in ethylene carbonate-methyl-ethyl carbonate/LiPF6 solutions. Our TEM studies revealed that typically, upon initial cycling both at 0 degrees c and 30 degrees c, Li2MnO3 underwent partial structural layered-to-spinel (Li2Mn2O4) transition.

关键词： lithium-ion batteries Li and Mn-rich materials Li2MnO3 activation at 0 ° c stabilized cycling decreased the voltage hysteresis layered-to-spinel transition bulk and surface characteristics

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MULTIPLE-TAPER SPEcTRAL-ANALYSIS - A STAND-ALONE c-SUBROUTINE

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cOMPUTERS & GEOScIENcES 1995年第2期21卷 199-236页

作者： LEES, JM PARK, J Department of Geology and Geophysics Yale University P.O. Box 208109 New Haven CT 06520-8109 U.S.A.

A simple set of subroutines in ANSI-c are presented for multiple taper spectrum estimation. The multitaper approach provides an optimal spectrum estimate by minimizing spectral leakage while reducing the variance of the estimate by averaging orthogonal eigenspectrum estimates. The orthogonal tapers are Slepian n pi prolate functions used as tapers on the windowed time series. Because the taper functions are orthogonal, combining them to achieve an average spectrum does not introduce spurious correlations as standard smoothed single-taper estimates do. Furthermore, estimates of the degrees of freedom and F-test values at each frequency provide diagnostics for determining levels of confidence in narrow band (single frequency) periodicities. The program provided is portable and has been tested on both Unix and Macintosh systems.

关键词： SPEcTRAL ANALYSIS MULTITAPER SPEcTRUM GEOLOGIcAL TIME SERIES c

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Advanced control-flow and concurrency in c∀

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SOFTWARE-PRAcTIcE & EXPERIENcE 2021年第5期51卷 1005-1042页

作者： Delisle, Thierry Buhr, Peter A. Univ Waterloo Cheriton Sch Comp Sci 200 Univ Ave West Waterloo ON N2L 3G1 Canada

c for all is a polymorphic, nonobject-oriented, concurrent, backwards compatible extension of the c programming language. This paper discusses the design philosophy and implementation of its advanced control-flow and concurrent/parallel features, along with the supporting runtime written in c for all. These features are created from scratch as ISO c has only low-level and/or unimplemented concurrency, so c programmers continue to rely on library approaches like pthreads. c for all introduces modern language-level control-flow mechanisms, like generators, coroutines, user-level threading, and monitors for mutual exclusion and synchronization. The runtime provides significant programmer simplification and safety by eliminating spurious wakeup and monitor barging. The runtime also ensures multiple monitors can be safely acquired in a deadlock-free way, and this feature is fully integrated with all monitor synchronization mechanisms. All control-flow features integrate with the c for all polymorphic type-system and exception handling, while respecting the expectations and style of c programmers. Experimental results show comparable performance of the new features with similar mechanisms in other concurrent programming languages.

关键词： c c∀ (cforall) coroutine concurrency generator monitor parallelism runtime thread

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Superior hydrogen generation from sodium borohydride hydrolysis catalyzed by the bimetallic co-Ru/c nanocomposite

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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY 2021年第50期46卷 25376-25384页

作者： Huang, Wenkai Xu, Fuhua Liu, Xiang China Three Gorges Univ Engn Res Ctr Ecoenvironm Three Gorges Reservoir R Key Lab Inorgan Nonmetall Crystalline & Energy Co Coll Mat & Chem EngnMinist Educ Yichang 443002 Hubei Peoples R China

Sodium borohydride has been widely regarded as a promising hydrogen carrier owing to its greatly hydrogen storing capability (10.8 wt%), high weight density and excellent stability in alkaline solutions. Herein, we first design and synthesize a series of bimetallic M-Ru/c nanocomposites (including Fe-Ru/c, co-Ru/c, Ni-Ru/c and cu-Ru/c), via simply alloying of commercial Ru/c with nonprecious metal, for superior H2 evolution from the NaBH4 hydrolysis. The result exhibits that H2 generation is synergetically improved by alloying Ru/ c with co or Ni, while it is hindered by alloying Ru/c with Fe or cu. Indeed, co-Ru/c presents the highest efficient catalytic activity for H2 generation, with the TOF of 117.69 mol(H2)center dot molRu-1 center dot min-1, whereas Ru/c is only 57.08 mol(H2)center dot molRu-1 center dot min-1. In addition, the TOF of co-Ru/c reaches to 436.51 mol(H2)center dot molRu-1 center dot min-1 (96.7 L(H2)center dot gRu-1 center dot min-1) in the presence of NaOH. (c) 2021 Hydrogen Energy Publications LLc. Published by Elsevier Ltd. All rights reserved.

关键词： Sodium borohydride Hydrogen co-Ru c Bimetallic Hydrolysis

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