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Coherence analysis of noise-like pulses generated by an erbium-doped fiber mode-locked laser

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Optoelectronics Letters 2024年第4期20卷 205-210页

作者： ZHANG Ziyi WANG Chuncan LI Jing WANG Peng Key Laboratory of All Optical Network and Advanced Telecommunication Network Ministry of EducationInstitute of Lightwave technologybeijing Jiaotong University Beijing 100044China

The noise-like pulses(NLPs)with tunable fraction of the pedestal height in the whole intensity autocorrelation(AC)trace are numerically demonstrated in the designed erbium-doped fiber(EDF)mode-locked laser,which contains the saturable absorber(SA)with nonlinear polarization rotation(NPR),sinusoidal-shaped or Gaussian-shaped filter,two segments of EDFs,and two pieces of single-mode fibers(SMFs)with normal dispersion and anomalous dispersion,*** pedestal ratio of the intensity AC trace can be tuned by changing the gain saturation energies of *** results show that when the net cavity dispersion is 1.06 ps^(2),the tuning range of the pedestal ratio for the NLPs can reach its maximum values,which are 0.51—0.89 and 0.58—0.88 for the sinusoidal-shaped and Gaussian-shaped filters,*** addition,an appropriate choice of filter bandwidth is also conducive to obtain a wide range of the tuning pedestal ratio for the intensity AC trace.

关键词： fiber tuning polarization

Anisotropic plastic deformation behavior of B2-ordered Fe_3Al single crystals at room temperature

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中国有色金属学会会刊：英文版 2002年第4期12卷 669-675页

作者：郑为为杨王玥孙祖庆 StateKeyLaboratoryforadvancedMetalsandMaterials UniversityofScience＆TechnologyBeijing100083China schoolofmaterialsscienceandengineering UniversityofScience＆TechnologyBeijingB

The tensile plastic deformation behavior of B2 ordered Fe 3Al single crystals at room temperature was systematically investigated. The results show that the mechanical properties are strongly orientation dependent. The plastic elongation of crystals with orientation near is as high as 42%. Slip trace analysis shows that although slip planes are found to change among {110} , {112} and {123} with the change in orientations, the initial slip planes in all cases are {110}. Five stage work hardening curve including four linear stages and one parabolic stage is obtained; but not all stages are observed in the actual deformation of each crystal. In combination with investigations of dislocation substructure, it is found that deformations in stage Ⅰ～Ⅲ are corresponding to the motion of two fold superdislocations. The higher work hardening rate of stage Ⅱ is mainly due to the stronger interactions between primary dislocations and secondary dislocations than those in stage Ⅲ. Deformation in stage Ⅳ involved is not only the motion of two fold superdislocations but also the slip of dissociated superpartials with APB traps and the formation of APB tube, both of which are attributed to the hardening. Deformation in stage Ⅴ is controlled by the cross slip of dissociated superpartials. The dominated softening effect of cross slip reduces the hardening rate and leads to the formation of parabolic stage.

关键词：室温 Fe3Al 金属间化合物塑性变形

Atomic scale KMC simulation of {100} oriented CVD diamond film growth under low substrate temperature-Part Ⅱ Simulation of CVD diamond film growth in C-H system and in Cl-containing systems

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Journal of University of Science and Technology Beijing 2002年第5期9卷 453-457页

作者： XizhongAn YuZhang 等 MaterialsScienceandengineeringSchool UniversityofScience＆TechnologyBeijingBeijing100083China AppliedScienceSchool UniversityofScience＆TechnologyBeijingBeijing100083China

The growth of {100}-oriented CVD diamond film under two modifications ofJ-B-H model at low substrate temperatures was simulated by using a revised KMC method at atomicscale. The results were compared both in Cl-containing systems and in C-H system as follows: (1)Substrate temperature can produce an important effect both on film deposition rate and on surfaceroughness; (2) Aomic Cl takes an active role for the growth of diamond film at low temperatures; (3){100}-oriented diamond film cannot deposit under single carbon insertion mechanism, which disagreeswith the predictions before; (4) The explanation of the exact role of atomic Cl is not provided inthe simulation results.

关键词： CVD diamond film atomic Cl revised KMC (kinetic monte carlo) method atomic scale simulation

Influence of Processing Parameters on Granularity Distribution of Superalloy Powders during PREP

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Journal of Materials Science & Technology 2003年第6期19卷 587-590页

作者： HuanmingCHEN BenfuHU YiwenZHANG HuiyingLI QuanmaoYU universityofscience&technologybeijing Beijing100083China CentralIronandSteelResearchInstitute Beijing100081China

In order to investigate the influence of processing parameters on the granularity distribution of superalloy powders during the atomization of plasma rotating electrode processing (PREP), in this paper FGH95 superalloy powders is prepared under different processing conditions by PREP and the influence of PREP processing parameters on the granularity distribution of FGH95 superalloy powders is discussed based on fractal geometry theory. The results show that with the increase of rotating velocity of the self-consuming electrode, the fractal dimension of the granularity distribution increases linearly, which results in the increase of the proportion of smaller powders. The change of interval between plasma gun and the self-consuming electrode has a little effect on the granularity distribution, also the fractal dimension of the granularity distribution changed a little correspondingly.

关键词： FGH95 superalloy powders Granularity distribution Plasma rotating electrode processing (PREP),Fractal dimension

Stress corrosion cracking and its anisotropy of a PZT ferroelectric ceramics

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Chinese Science Bulletin 2003年第12期48卷 1203-1206页

作者： WANGYi CHUWuyang SUYanjing GAOKewei QIAOLijie DepartmentofMaterialsPhysics UniversityofScience&TechnologyBeijingBeijing100083China

Stress corrosion cracking (SCC) of a PZT ferroelectric ceramics in various media, such as moist atmosphere, silicon oil, methanol, water and formamide, and its anisotropy have been investigated at constant load test using a single-edge notched tensile specimen. The results showed that SCC could occur in all media, and the threshold stress intensity factor of SCC in water and formamide, KISCC, revealed anisotropy. The KISCC for poling direction parallel to the crack plane, was greater than that perpendicular to the crack plane, similar to the anisotropy of fracture toughness KIC; however, the anisotropy factor of KISCC, which was =1.8 (in formamide) and 2.1 (in water), was larger than that of KIC, which is =1.4. The stress-induced 90° domain switching causes the anisotropy of KIC and KISCC, besides, the resistance of SCC also has anisotropy.

关键词：铁电陶瓷各向异性应力腐蚀碎裂 PZT 阈值应力强度因子

Electrochemical performance of nickel oxide/KOH/active carbon super-capacitor

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Journal of University of Science and Technology Beijing 2002年第4期9卷 277-281页

作者： XiaofengWang DazhiWang CuiweiDo XianghuaKong QingguoLiu Departmentofmechanicalengineering TsinghuaUniversityBeijing100084China StateSupportLaboratoryonSolidElectrolytesandMetallutgica''lTestingTechniques UniversityofScience&TechnologyBeijingBeijing100083China

The fabrication and characterization of new type Nickel oxide/KOH/Activecarbon super-capacitor have been described. Porous nickel oxide was prepared by hydrolysis of nickelacetate and heated in air at 300 deg C. The resulting nickel oxide behaved as an electrochemicalcapacitor electrode with a specific capacitance (50-70 F/g) superior to most active carbonelectrodes. This kind of nickel oxide maintained high utilization at high rate of discharge (i.e.,high power density) and had excellent cycle life more than 1000 times, while the capacitance of thecell composed of two identical nickel oxide electrodes was poor at high discharge current densityand the maximum operational voltage of this type capacitor was limited to 0.5 V. A new typesuper-capacitor was designed in which the nickel oxide and the active carbon were applied to thepositive and negative electrodes respectively. The breakdown voltage of this type super-capacitorwas improved effectively to 0.8 V and excellent characteristic of high power discharge was attainedin this way. The Nickel oxide/KOH/Active carbon super-capacitor has promising potentials in portabletelecommunications, uninterruptable power supplies and battery load leveling applications.

关键词： nickel oxide active carbon super-capacitor pseudo-capacitance

Mechanism of a-Cr Formation in Nickel-Base Superalloy INCONE1718 after Long Time Thermal Exposure

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材料热处理学报 2004年第5期25卷 225-228页

作者： WANGGai-fian XIEXi-shan HighTemperatureMaterialsResearchLab UniversityofScience＆TechnologyBeijingBeijingChina

It is commonly accepted that the drop in mechanical properties of INCONE1718(IN718) after long time exposure at high temperature is a result of coalescence of y", ?/ and the transformation of y" to 8-Ni3Nb phase. Besides the 7", ?/ and , the precipitation of B.C.C. -Cr is another factor that affects the mechanical properties of IN718. In this paper, the Thermal-Calc software is used to reveal the thermodynamic condition of -Cr formation. The calculated sections of the pseudo ternary diagrams of Cr-Nb-IN718 and Cr-Fe-IN718 explain why -Cr particles do not precipitate dispersedly in matrix but in the vicinity of phase. The selected area diffraction (SAD) of TEM confirms the crystallography relationship of -Crwith is (010) g// (-110) ***, [100] s//[Hl] a-cr? In combination of TTT diagram with the Thermal-Calc and TEM results, the mechanism of -Cr formation in IN718 is suggested.

关键词： INCONEI718 α-Cr相位镍合金热石灰质热暴露

Thermal　Conductivity　Measurement　of　Semitransparent　Media　at　Temperatures　from　300　to　800　K　by　Hot－Wire　Method

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Journal of Thermal Science 1996年第1期5卷 11-15页

作者： XinxinZhang FanYu 等 DepartmentofEnergyengineering UniversityofScience＆TechnologyBeijing100083BeijingCHian DepartmentofEn

In this paper,a new measurement technique for determining thermal conductivity of semitransparent media in the temperature range 300-800 K is *** experimental setup is based on the step power forced transient hot wire *** is assumed that the radiative contribution to the heat transfer process arises from emission,not from *** this case,application of the'thermal quadruples'method allows a very simple construction of analytical models of the experimental *** parameter sensitivity analysis demonstrates that the thermal conductivity of semitransparent media can be determined from the hot wire temperature response. The experimental results of a kind of glass between 300 and 800 K are presented.

关键词： thermal conductivity semitransparent medium hot wire method radiationconduction heat transfer.

Hydrogen-induced Cracking of Weld Metal of Austenitic Stainless Steels

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Journal of Materials Science & Technology 2002年第4期18卷 375-377页

作者： ChuanPAN LijieQIAO 等 DepartmentofWeldingResearch CentralIorn&SteelResearchInstituteBeijing100081China DepartmentofMaterialsPhysics UniversityofScience&TechnologyBeijingBeijing100083China

For 308L and 347L weld metals of austenitc stainless steels (ASS), hydrogen induced cracking (HIC) occurred during dynamically charging under constant load. The threshold stress intensity for HIC, Km, decreased linearly with the logarithm of the concentration of diffusible hydrogen C0 in the weld metals and the rolled plate of type 304L ASS, i.e., KIH=85.2-10.71nC0 (308L), KIH=76.1-9.31n C0(347L), and KIH=91.7-10.11nC0(304L). The fracture mode for HIC in the three type of ASS changed from ductile to brittle with the decrease in the applied stress intensity KI or/and the increase in C0. The boundary line between ductile and brittle fracture surfaces was KI-54+25exp(-C0/153)=0.

关键词： Austenitic stainless steel Hydrogen induced cracking Fracture