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Shortening the Duration of heat Treatment in the Lower Bainitic range

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材料热处理学报 2004年第5期25卷 555-560页

作者： h. Vetters h.-w. Zoch Foundation Institute for Materials Science Bremen GermanyFoundation Institute for Materials Science Bremen Germany

In many cases an isothermal treatment of throughhardening bearing grades in the lower bainitic range allows to adjust the mechanical properties of machine components to the later application, similar to those of martensitic hardening. The achieved microstructure contains only a negligible amount of retained austenite, so a dimensional change of components during application can be reduced. One disadvantage of the isothermal bainitic treatment in salt bath is that the duration of the treatment is much longer than that of the martensitic hardening and this causes higher costs. Therefore it would be desirable to be able to shorten the transformation duration in the lower bainitic range. The aim of the present work is to determine the parameters, by which the process could be greatly shortened in comparison with the conventional transformation process in the lower bainitic range. Therefore the bainitic transformation behavior of the steel 100 Cr6 (SAE 52100) and the relevant influence factors were investigated by means of dilatometry, in which the heat treatments were carried out with different process variants including pre-quenching or post-quenching. The amount of retained austenite in the microstructure and the hardness of the steel after the shortened heat treatments were measured. Finally the possibility to use these processes in industrial production is discussed.

关键词：贝氏体轴承钢膨胀测定法热处理

Gorenstein Projective Modules over Triangular Matrix rings

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Algebra Colloquium 2016年第1期23卷 97-104页

作者： h. Eshraghi r. hafezi Sh. Salarian Z.w. Li Department of Pure Mathematics Faculty of Mathematical Sciences University of Kashan P.O. Box 87317-51167 Kashan Iran School of Mathematics Institute for Research in Fundamental Sciences (IPM) P.O. Box 19395-5746 Tehran Iran Department of Mathematics University of Isfahan P.O. Box 81746-73441 Isfahan Iran School of Mathematics Institute for Research in Fundarnental Sciences (IPM) P.O. Box 19395-5746 Tehran Iran Department of Mathematics Jiangsu Normal University Xuzhou 221116 China

Let r and S be Artin algebras and F be their triangular matrix extension via a bimodule sMr. we study totally acyclic complexes of projective F-modules and obtain a complete description of Gorenstein projective F-modu... 详细信息

关键词： Gorenstein projective totally acyclic Cohen-Macaulay finite

Flux penetration of an hTS coated-conductor tape by an approaching permanent magnet

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Superconductivity 2022年第4期4卷 41-50页

作者： r.w.Taylor T.Booth M.D.Ainslie h.w.weijers r.A.Badcock C.w.Bumby Paihau-robinson research Institute Victoria University of WellingtonLower Hutt 5010New Zealand MacDiarmid Institute Victoria University of WellingtonWellington 6140New Zealand Department of Engineering King’s College LondonLondon WC2R 2LSUnited Kingdom

Interactions between inhomogeneous magnetic fields and a superconductor lie at the heart of several high‐temperature superconducting(hTS)*** example is the situation where the magnetic field from a small permanent magnet(PM)is applied to a coated‐conductor hTS tape,such that flux penetrates the *** PM field is highly spatially inhomogeneous,such that there is significant variation in the applied field magnitude and direction across the *** leads to a varying local critical current density,J_(c)(B,θ),across the tape,and consequently different‘shielding’(magnetic flux penetration)behaviour than is the case for a uniform applied ***,we report results from measurements and numerical simulations of the penetrating magnetic field within an hTS coated‐conductor tape which occur as a PM dipole approaches from a *** simulations were performed using a finite‐element model based on the h‐formulation,and which incorporated experimentally‐measured anisotropic J_(c)(B,θ)Þproperties from a coated‐conductor *** showed good agreement with experimental *** effects of varying key modelling assumptions and parameters were then studied,including changing the widths of the PM and hTS tape and the magnitude of J_(c)(B,θ).The inhomogeneity of the PM field leads to a characteristic gull‐wing distribution of magnetic flux across the superconductor at elevated applied *** approach of the PM to the tape suppresses Jc in the centre of the tape,and this results in the observation of a characteristic maxima for the total shielding currents circulating in the tape.A figure of merit is introduced which uses this effect to provide a threshold definition for‘full flux penetration’of an hTS tape by an inhomogeneous dipole field.

关键词： Coated conductor high temperature superconductors hTS modelling Finite‐element method

Extension/Compression-Controlled Complete Band Gaps in 2D Chiral Square-Lattice-Like Structures

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Acta Mechanica Solida Sinica 2018年第1期31卷 51-65页

作者： Y. L. huang N. Gao w.Q. Chen r.h. Bao Department of Engineering Mechanics Zhejiang University Hangzhou 310027 China State Key Lab of CAD & CG Zhejiang University Hangzhou 310058 China Key Laboratory of Soft Machines and Smart Devices of Zhejiang Province Zhejiang University Hangzhou 310027 China Soft Matter research Center Zhejiang University Hangzhou 310027 China

Achieving tunable band gaps in a structure by external stimuli is of great importance in acoustic applications. This paper aims to investigate the tunability of band gaps in square-lattice-like elastic periodic structures that are usually not featured with notable band gaps. Endowed with chirality, the periodic structures here are able to undergo imperfection-insensitive large deformation under extension or compression. The influences of geometric parameters on band gaps are discussed via the nonlinear finite element method. It is shown that the band gaps in such structures with curved beams can be very rich and, more importantly, can be efficiently and robustly tuned by applying appropriate mechanical loadings without inducing buckling. As expected, geometry plays a more significant role than material nonlinearity does in the evolution of band gaps. The dynamic tunability of band gaps through mechanical loading is further studied. results show that closing, opening, and shifting of band gaps can be realized by exerting real-time global extension or compression on the structure. The proposed periodic structure with well-designed chiral symmetry can be useful in the design of particular acoustic devices.

关键词： Band gap Tunability Square-lattice-like periodic structure Chiral symmetry,Large deformation

MOLECULAr DYNAMICS SIMULATION OF STrUCTUrE STABILITY OF SILVEr NANOCLUSTErS

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Acta Metallurgica Sinica(English Letters) 2006年第3期19卷 209-214页

作者： w.h. Qi School of Materials Science and Engineering Jiangsu University Zhenjiang 212013 China School of Materials Science and Engineering Central South University Changsha 410083 China

The structures of Ag clusters with sizes n=13 to 1157 are studied by tight binding molecular dynamics simulation. It is found that the stable structures of Ag clusters follow the sequence amorphous-crystalline-amorphous-crystalline with the cluster size increasing from 13 to 1157. Furthermore, all the shells of Ag clusters are different from the structure of the corresponding bulk Ag.

关键词： structure stability molecular dynamics silver nanoclusters

MODELING OF DYNAMIC rECrYSTALLIZATION OF Ti6A14V ALLOY USING A CELLULAr AUTOMATON APPrOACh

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Acta Metallurgica Sinica(English Letters) 2008年第4期21卷 260-268页

作者： J.w. Zhao h. Ding w.J. Zhao F.r. Cao h.L. hou Z.Q. Li School of Materials and Metallurgy Northeastern University Shenyang 110004 China Beijing Aeronautical Manufacturing Technology research Institute Beijing 100024 China

A cellular automaton （CA） model is established to simulate dynamic recrystallization （DrX） in the β single-phase field of Ti6Al4 V alloy, and the kinetics during DrX processing has been analyzed. The model employed considers the influences of dynamic recovery, nucleation rate, strain rate and dislocation density on DrX, and practical deformation parameters, such as temperature, strain and strain rate on DrX have been considered in the simulation. The simulated DrX grain size and DrX grain shape agree well with the experimental results, which shows the availability and lea- sibility of the cellular automaton method for the simulation of DrX. The result of kinetics analysis of DrX reveals that the Avrami exponent is variable ranging from 2.4 to 2.9, which increases with the increase of strain rate.

关键词： Ti6A4 V alloyi Dynamic recrystallization Kinetics Modeling Cellular automaton

Nanosecond Pulse Generation with Silver Nanoparticle Saturable Absorber

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Chinese Physics Letters 2019年第5期36卷 31-34页

作者： r.Z.r.r.rosdin M.T.Ahmad A.r.Muhammad Z.Jusoh h.Arof S.w.harun Photonics Engineering Laboratory Department of Electrical Engineering University of Malaya Faculty of Electrical Engineering Universiti Teknologi Mara (Terengganu) Department of Physics Faculty of Science and Technology Airlangga University

Nanosecond pulse generation in an erbium-doped fiber laser (EDFL) passively mode-locked by a silver nanoparticle(SNP)-based saturable absorber(SA) is experimentally demonstrated. The SA is fabricated by depositing a nanosized SNP layer onto the surface of polyvinyl alcohol film through the thermal evaporation process. By inserting the SA into an EDFL cavity, stable mode-locked operation is achieved at 1561.5 nm with the maximum pulse energy up to 52.3 nJ. The laser operates at a pulse repetition frequency of 1.0 Mhz with a pulse width of 202 ns. These results suggest that SNPs could be developed as an effective SA for mode-locking pulse generation.

关键词： SA Nanosecond Pulse Generation with Silver Nanoparticle Saturable Absorber

hIGh TEMPErATUrE FATIGUE BEhAVIOUr OF A DIrECTIONALLY SOLIDIFIED COBALT-BASE SUPErALLOY

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Acta Metallurgica Sinica(English Letters) 1998年第2期11卷 111-115页

作者： w.h.JIANG X.D.YAO h.r.GUAN Z.Q.hU Chinese Acad of Sciences Shenyang China

The high temperature high cycle fatigue behaviour of a directionally solidified Co-base superalloy was investigated. The alloy has saperior fatigue resistance at 900℃ and its fatigue strength is up to 295MPa. Its σ-Nf curve is characterized by three distinct zones. The stronger dependence of Nf on or in the high .and low stress zones results from multiple fatigue crock initiation sites produced by high stress and oxidation effect in a prolonged exposure, respectively.

关键词： directional solidification Co-base superalloy fatigue fracture

Passively Q-Switched EDFL Using a Multi-walled Carbon Nanotube Polymer Composite Based on a Saturable Absorber

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Chinese Physics Letters 2014年第3期31卷 69-72页

作者： F. Ahmad h. haris r. M. Nor N. r. Zulkepely h. Ahmad S. w. harun Department of Electrical Engineering University of Malaya Kuala Lumpur 50603 Malaysia Photonics research Centre University of Malaya Kuala Lumpur 50603 Malaysia Department of Physics University of Malaya Kuala Lumpur 50603 Malaysia

A stable passive Q-switched erbium-doped fiber laser （EDFL） operating at 1563.5 nm is demonstrated by using a multi-walled carbon nanotube （MwCNT） polymer composite film based saturable absorber for the first time. The composite is prepared by mixing the MwCNTs homogeneous solution into a dilute PEO polymer solution before it is left to dry at room temperature to produce thin film. Then the film is sandwiched between two FC/PC fiber connectors and is integrated into the laser cavity for Q-switching pulse generation. The EDFL generates a stable pulse train with repetition rates ranging from 4.5 khz to 20.0 khz by varying the 1480 nm pump power from 35 mw to 53 mw. At the 53 mw pump power, the pulse width and pulse energy are 8.8 μs and 15.3 nJ, respectively.

关键词： Saturable absorbers