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Atomic-scale understanding of martensitic transformation and transition-induced twinning in deformed Fe-Mn alloys
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作者 ZHANG Hong-bo LI Hong-kui +2 位作者 OU Xiao-qin SHEN Jie SONG Min 《Journal of Central South University》 2025年第4期1211-1222,共12页
In the present study,molecular dynamic simulation(MD)was used to investigate the plastic deformation process of the Fe-Mn alloys with different Mn contents.The influences of Mn contents ranging from 10%to 30%(at%)on t... In the present study,molecular dynamic simulation(MD)was used to investigate the plastic deformation process of the Fe-Mn alloys with different Mn contents.The influences of Mn contents ranging from 10%to 30%(at%)on the deformation behavior and the controlling mechanism of the Fe-base alloys were analyzed.The results show that phase transformations and{112}<111>_(BCC)deformation twinning occur in all Fe-Mn alloys but follow different deformation paths.In the Fe-10%Mn alloy the deformation twinning mechanism obeys the FCC-related path,the Fe-20%Mn alloy involves both the FCC-and HCP-related paths,and the deformation of the Fe-30%Mn alloy is dominated by the HCP-related twinning path.The addition of Mn can increase the stacking fault energy and retard the activation of slip systems as well as the formation of stacking faults.Thus,a higher content of Mn can delay the FCC®ε-martensite and the subsequentε-martensite®BCC phase transition at the intersection of twoε-martensitic bands.Therefore,the addition of Mn alloying element increases the yield strength and reduces the elastic modulus of the Fe-Mn alloys.The formation of deformation twins will contribute to the work-hardening effect and delay the necking and fracture of alloys.It is expected that the results in the present study will provide theoretical reference for the design and optimization of high-performance steels. 展开更多
关键词 Fe-Mn steel tensile deformation molecular dynamics simulation phase transformation
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Phase error analysis and optimization for chirp transform spectrometer
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作者 RU Penglei LIU Mengwei +1 位作者 HU Baifan WANG Wen 《Journal of Systems Engineering and Electronics》 2025年第3期597-608,共12页
In the field of deep space exploration,the rapid development of terahertz spectrometer has put forward higher requirements to the back-end chirp transform spectrometer(CTS)system.In order to simultaneously meet the me... In the field of deep space exploration,the rapid development of terahertz spectrometer has put forward higher requirements to the back-end chirp transform spectrometer(CTS)system.In order to simultaneously meet the measurement requirements of wide bandwidth and high accuracy spectral lines,we built a CTS system with an analysis bandwidth of 1 GHz and a frequency resolution of 100 kHz around the surface acoustic wave(SAW)chirp filter with a bandwidth of 1 GHz.In this paper,the relationship between the CTS nonlinear phase error shift model and the basic measurement parameters is studied,and the effect of CTS phase mismatch on the pulse compression waveform is analyzed by simulation.And the expander error optimization method is proposed for the problem that the large nonlinear error of the expander leads to the unbalanced response of the CTS system and the serious distortion of the compressed pulse waveform under large bandwidth.It is verified through simulation and experiment that the method is effective for reducing the root mean square error(RMSE)of the phase of the expander from 18.75°to 6.65°,reducing the in-band standard deviation of the CTS frequency resolution index from 8.43 kHz to 4.72 kHz,solving the problem of serious distortion of the compressed pulse waveform,and improving the uneven CTS response under large bandwidth. 展开更多
关键词 chirp transform spectrometer(CTS) microwave heterodyne spectroscopy phase error compensation surface acoustic wave(SAW) wide bandwidth
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Phase transformation in suspension roasting of oolitic hematite ore 被引量:8
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作者 李艳军 王儒 +1 位作者 韩跃新 魏新超 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第12期4560-4565,共6页
Suspension roasting followed by magnetic separation is a promising method to upgrade oolitic hematite ore.An oolitic hematite ore was roasted using suspension roasting technology at different temperatures.The phase tr... Suspension roasting followed by magnetic separation is a promising method to upgrade oolitic hematite ore.An oolitic hematite ore was roasted using suspension roasting technology at different temperatures.The phase transformation for iron minerals was investigated by XRD and Mossbauer spectrum,and the characteristics of roasted product were analyzed by VSM and SEM-EDS.Results indicate that the magnetic concentrate is of 58.73% Fe with iron recovery of 83.96% at 650 °C.The hematite is rapidly transformed into magnetite during the roasting with transformation ratio of 92.75% at 650 °C.Roasting temperature has a significant influence on the phase transformation of hematite to magnetite.The transformation ratio increases with increased temperature.After roasting,the magnetic susceptibility is significantly improved,while iron ore microstructure is not altered significantly. 展开更多
关键词 oolitic hematite ore suspension roasting Mossbauer spectrum magnetic property phase transformation
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Siderite pyrolysis in suspension roasting:An in-situ study on kinetics,phase transformation,and product properties 被引量:6
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作者 ZHANG Qi SUN Yong-sheng +2 位作者 QIN Yong-hong GAO Peng YUAN Shuai 《Journal of Central South University》 SCIE EI CAS CSCD 2022年第6期1749-1760,共12页
Siderite,as an abundant iron ore,has not been effectively utilized,with a low utilization rate.In this study,the in-situ kinetics and mechanism of siderite during suspension magnetization roasting(SMR)were investigate... Siderite,as an abundant iron ore,has not been effectively utilized,with a low utilization rate.In this study,the in-situ kinetics and mechanism of siderite during suspension magnetization roasting(SMR)were investigated to improve the selective conversion of siderite to magnetite and CO,enriching the theoretical system of green SMR using siderite as a reductant.According to the gas products analyses,the peak value of the reaction rate increased with increasing temperature,and its curves presented the feature of an early peak and long tail.The mechanism function of the siderite pyrolysis was the contraction sphere model(R_(3)):f(α)=3(1−α)2/3;E_(α)was 46.4653 kJ/mol;A was 0.5938 s^(−1);the kinetics equation was k=0.5938exp[−46.4653/(RT)].The in-situ HT-XRD results indicated that siderite was converted into magnetite and wüstite that exhibited a good crystallinity in SMR under a N_(2) atmosphere.At 620℃,the saturation magnetization(M_(s)),remanence magnetization(Mr),and coercivity(Hc)of the product peaked at 53.63×10^(-3)A·m^(2)/g,10.23×10^(-3)A·m^(2)/g,and 12.40×10^(3)A/m,respectively.Meanwhile,the initial particles with a smooth surface were transformed into particles with a porous and loose structure in the roasting process,which would contribute to reducing the grinding cost. 展开更多
关键词 SIDERITE suspension magnetization roasting reaction kinetics phase transformation magnetic transition microstructure evolution
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Effects of tensile temperatures on phase transformations in zirconium by molecular dynamics simulations 被引量:1
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作者 AN Ke-ying OU Xiao-qin +3 位作者 AN Xing-long ZHANG Hao NI Song SONG Min 《Journal of Central South University》 SCIE EI CAS CSCD 2021年第7期1932-1945,共14页
The effects of tensile temperatures ranging from 100 K to 900 K on the phase transition of hexagonal close-packed(HCP)zirconium were investigated by molecular dynamics simulations,which were combined with experimental... The effects of tensile temperatures ranging from 100 K to 900 K on the phase transition of hexagonal close-packed(HCP)zirconium were investigated by molecular dynamics simulations,which were combined with experimental observation under high resolution transmission electron microscopy.The results show that externally applied loading first induced the HCP to body-centered cubic(BCC)phase transition in the Pitsch-Schrader(PS)orientation relationship(OR).Then,the face-centered cubic(FCC)structure transformed from the BCC phase in the Bain path.However,the HCP-to-BCC transition was incomplete at 100 K and 300 K,resulting in a prismatic-type OR between the FCC and original HCP phase.Additionally,at the temperature ranging from 100 K to 600 K,the inverse BCC-to-HCP transition occurred locally following other variants of the PS OR,resulting in a basal-type relation between the newly generated HCP and FCC phases.A higher tensile temperature promoted the amount of FCC phase transforming into the BCC phase when the strain exceeded 45%.Besides,the crystal stretched at lower temperatures exhibits relatively higher strength but by the compromise of plasticity.This study reveals the deformation mechanisms in HCP-Zr at different temperatures,which may provide a better understanding of the deformation mechanism of zirconium alloys under different application environments. 展开更多
关键词 ZIRCONIUM phase transformation molecular dynamics simulation deformation mechanism tensile temperature
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Phase transformation of nano-grained W(Co, C) composite powder and its phase constitute 被引量:1
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作者 曹顺华 蔡志勇 +2 位作者 周建华 李炯义 林信平 《Journal of Central South University of Technology》 EI 2006年第6期603-607,共5页
A new process of WC-Co cemented carbide was developed by using nano-grained W(Co, C) composite powders as raw materials processed by high-energy ball milling. X-ray diffraetion(XRD), differential thermal analysis ... A new process of WC-Co cemented carbide was developed by using nano-grained W(Co, C) composite powders as raw materials processed by high-energy ball milling. X-ray diffraetion(XRD), differential thermal analysis (DTA), thermo-gravimetrie (TG) analysis and coercive forces of the sintered samples were adopted to analyze the phase transformation and constitution, and the microstructures of sintered samples were characterized by scanning electron microscopy(SEM). The results show that the as-milled powders are transformed into transitional phases W2C and η (Co3W3C or Co6W6C) during sintering, and finally transformed into WC and Co phases completely at 1 250℃ for 30 min, and a large number of fibrous WC grains with about 1.2μm in length and 100 nm in radial dimension are formed in the sintered body at 1 300 ℃. 展开更多
关键词 cemented carbide phase transformation high-energy ball milling fibrous WC grain
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Effect of high magnetic field on phase transformation temperature and microstructure of Fe-based Alloys 被引量:13
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作者 郝新江 OHTSUKA Hideyuki 《材料与冶金学报》 CAS 2005年第2期132-137,共6页
The effect of a high magnetic field up to 30T on phase transformation temperature and microstructure of Fe-based alloys has been reviewed. A high magnetic field accelerates ferrite transformation, changes the morpho... The effect of a high magnetic field up to 30T on phase transformation temperature and microstructure of Fe-based alloys has been reviewed. A high magnetic field accelerates ferrite transformation, changes the morphology of the transformed microstructures and increases the A3 and A1 temperature. In a magnetic field of 30T, the A1 temperature increases by about 37.1℃ for Fe-0.8C, the A3 temperature for pure Fe increases by about 33.1℃. The measured transformation temperature data are not consistent with calculation results using Weiss molecular field theory. Ferrite grains are elongated and aligned along the direction of magnetic field in Fe-0.4C and Fe-0.6C alloys by ferrite transformation, but elongated and aligned structure was not found in pure Fe, Fe-0.05C alloy and Fe-1.5Mn-0.11C-0.1V alloy. 展开更多
关键词 强磁场 铁基合金 相变温度 显微组织
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Calculation of Phase Transformation Kinetics from Dilatation Curves
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作者 Mesplont C De Cooman B C 《厦门大学学报(自然科学版)》 CAS CSCD 北大核心 2002年第S1期15-16,共2页
The structure of a steel changes with temperature due to phase transformations. This phase change is generally companied by a variation in the specific volume which is exhibited as a departure from the behaviour of th... The structure of a steel changes with temperature due to phase transformations. This phase change is generally companied by a variation in the specific volume which is exhibited as a departure from the behaviour of the thermal expansion or contraction, at the temperature at which the change occurs. This behaviour can be detected as a change in the dimensions of a suitable test piece, and forms the operating principle of dilatometry. The dilatometric technique may be applicable to the investigation of the phase transformation kinetics if the relation between the fractions of phases, the temperature, the compositions of phases and the dilatation can be built up. Efforts have been made to analyze the dilatation during an isothermal transformation or to calculate the dilatation during the heating of plain carbon steels using the thermodynamic function. The existing models are, however, not directly applicable to the determination of the phase transformation kinetics from a dilatation curve. A detailed analysis has been made of the length change of a hypoeutectoid steel during a continuous cooling. A model has been developed in which the transient dilatation is calculated based on the fraction of the phases present. The model takes into account the redistribution of carbon and is applicable to the determination of the phase transformation kinetics from the dilatation data during a cooling of a hypo-eutectoid steel. The model was validated by comparing the model results with the experimental results of an interstitial free steel. Experiments have been done with an interstitial-free steel and a C-Mn steel. The model has been applied to the calculation of the transformation kinetics indicated by the dilatation curves. Excellent agreements between the model and the experiments have been obtained. 展开更多
关键词 STEELS DILATATION modelling MULTISTEP phase transformation KINETICS
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Rehydration and Phase Transformation of Aluminas
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作者 Zhang Minghai, Li Guanghui, Ye Gang (Research Institute of Petroleum Processing, Beijing 100083) 《石油学报(石油加工)》 EI CAS CSCD 北大核心 1997年第S1期108-112,共5页
RehydrationandPhaseTransformationofAluminasZhangMinghai,LiGuanghui,YeGang(ResearchInstituteofPetroleumProces... RehydrationandPhaseTransformationofAluminasZhangMinghai,LiGuanghui,YeGang(ResearchInstituteofPetroleumProcesing,Beijing100083... 展开更多
关键词 ALUMINA REHYDRATION phase transformation BOEHMITE CORUNDUM
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Preparation and Phase Transformation Behavior of Boehmite via Heat Treatment in Water Vapor
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作者 CHEN Bo XU Xisheng +1 位作者 CHEN Xiaoming LU Xiancai 《矿物学报》 CAS CSCD 北大核心 2013年第S1期11-11,共1页
Boehmite was prepared under heat treatment in water vapour, and the phase transformation of gibbsite heat-treated at various temperatures was investigated. The sample was characterized by scanning electron microscopy(... Boehmite was prepared under heat treatment in water vapour, and the phase transformation of gibbsite heat-treated at various temperatures was investigated. The sample was characterized by scanning electron microscopy(SEM), X-ray diffraction (XRD), thermogravimetry and differential thermalanalysis (TG-DTA), fourier transform infrared (FTIR),and BET surface area.Effect of temperature on preparation was studied in the range of 155°–195°.With the increase in temperature, transformation of gibbsite into crystalline boehmites took place as indicated by the X-ray diffraction (XRD). The shape of the grains in the prepared sample was cube-like morphology.In water vapour gibbsite transform into boehmite by a dissolution - precipitation mechanism. 展开更多
关键词 GIBBSITE BOEHMITE water VAPOUR phase transformation
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Controllable phase transition of Al^(3+)induced manganese dioxide fromβ-toδ-type and their Al-dopedδ-type manganese dioxide for high-performance asymmetric supercapacitors
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作者 CHENG Xiao-yang ZHANG Li-hua +4 位作者 LI Ling-yan WU Hao ZHENG Jin-feng YAO Jia-rong LI Gui-fang 《Journal of Central South University》 2025年第6期2101-2113,共13页
Al-doped manganese dioxide(MnO_(2))was synthesized by simple hydrothermal method,and a controllable phase transition of the MnO_(2)crystal phase fromβtoδwas achieved.The effects of Al doping concentration on the str... Al-doped manganese dioxide(MnO_(2))was synthesized by simple hydrothermal method,and a controllable phase transition of the MnO_(2)crystal phase fromβtoδwas achieved.The effects of Al doping concentration on the structure and electrochemical properties of electrode materials were studied in detail.The results show that the controlled synthesis requires a synergy between KMnO_(4),MnCl_(2)and AlCl_(3),and that Al^(3+)plays an important role.Compared with the pure phase MnO_(2),the crystallinity of Al-doped MnO_(2)decreases and the specific surface area increases,which provides more active sites for the electrode material.When 3 mmol Al^(3+)is added,the prepared MnO_(2)-3 has the largest specific capacitance and the highest rate performance.The energy density of the asymmetric supercapacitor(ASC)with MnO_(2)-3 as the positive electrode and activated carbon(AC)as the negative electrode can reach 18.4 W·h/kg at the power density of 400 W/kg,and the capacity can maintain 90%of the initial value after 20000 cycles,indicating that Al-doped MnO_(2)has certain practical application value.This study provides favorable guidance for MnO_(2)as a high performance electrode material. 展开更多
关键词 Al doping MnO 2 phase transformation energy storage SUPERCAPACITOR
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Phase transformation of Al-Zn (Cu) alloys and the phase diagram of Al-Zn-Cu system
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作者 郝士明 《材料与冶金学报》 CAS 2005年第2期92-101,共10页
The room temperature phase diagram of Al-Zn-Cu system is the important basis for judging the phase constituents of the materials at the usage condition. New results about the room temperature phase diagram of the low ... The room temperature phase diagram of Al-Zn-Cu system is the important basis for judging the phase constituents of the materials at the usage condition. New results about the room temperature phase diagram of the low copper side in the Al-Zn-Cu systems have been shown in this study. Miscibility gap of fcc phase in the Al-Zn-Cu system has also been studied by experimental diffusion-couple method and thermodynamic calculation. Properties of this miscibility gap have been known. It is practically significant for the study on the aging behavior and for the control of the microstructure and properties of the Al alloys with Zn and Cu element. 展开更多
关键词 AL-ZN合金 相变 A1-Zn-Cu系 相图
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In-situ observations on interphase boundary migration and grain growth during α/γ phase transformation in iron-4.2%Cr alloy
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作者 渡边忠雄 OBARA Kouichi TSUREKAWA Sadahiro 《材料与冶金学报》 CAS 2005年第2期91-91,共1页
In-situ observations on α/γ phase transformation were made to study the effects of grain boundary microstructures on the formation of a new phase and the migration of α/γ interphase boundary in an iron4. 2%Cr allo... In-situ observations on α/γ phase transformation were made to study the effects of grain boundary microstructures on the formation of a new phase and the migration of α/γ interphase boundary in an iron4. 2%Cr alloy. It was found that triple junctions with more random boundaries could be the primary nucleation sites for a new phase, while triple junctions with low angle or low ∑ coincidence boundaries did not play any role as preferential sites. The migration of α/γ interphase boundary during heating over the transformation temperature range showed the two stage behaviour characterized by a stage with a migration velocity of 0. 33-0. 75 mm/s and secondly by a stage with 3. 7-7. 6 mm/s. It was also found that abnormal grain growth and a high density of ∑3 coincidence boundaries could occur in a phase with bcc structure after cycling of α/γ phase transformation. A new mechanism of nucleation and growth of a new phase in α/γ phase transformation is proposed on the basis of roles of plane-matching interphase boundaries, as previously discussed on the origin of anisotropy of grain growth due to the migration of {110} plane-matching boundaries in Fe-3z%Si alloy. The most recent theoretical work on the distribution of plane-matching boundaries in solids with different crystal structures was found to be useful for the understanding of nucleation and growth during α/γ phase transformation. 展开更多
关键词 In-situ phase velocity stage effects crystal with random origin the range after new was more play over high MOST for The to DID BCC It be
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结合极化自注意力和Transformer的结直肠息肉分割方法 被引量:1
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作者 谢斌 刘阳倩 李俞霖 《光电工程》 CAS CSCD 北大核心 2024年第10期87-101,共15页
针对传统结直肠息肉图像分割方法存在的目标分割不够精确、对比度不足,以及边缘细节模糊等问题,文中结合极化自注意力和Transformer提出了一种新的结直肠息肉图像分割方法。首先,设计了一种改进的相位感知混合模块,通过动态捕捉Transfor... 针对传统结直肠息肉图像分割方法存在的目标分割不够精确、对比度不足,以及边缘细节模糊等问题,文中结合极化自注意力和Transformer提出了一种新的结直肠息肉图像分割方法。首先,设计了一种改进的相位感知混合模块,通过动态捕捉Transformer结直肠息肉图像的多尺度上下文信息,以使目标分割更加精确。其次,在新方法中引入了极化自注意力机制,实现了图像的自我注意力强化,使得到的图像特征可以直接用于息肉分割任务中,以达到提高病灶区域与正常组织区域对比度的目的。另外,利用线索交叉融合模块加强动态分割时对图像几何结构的捕捉能力,以达到提升结果图像边缘细节的目的。实验结果表明,文中提出的方法不仅能够有效地提升结直肠息肉分割的精确度和对比度,并且还能够较好地克服分割图像细节模糊的问题。在数据集CVC-ClinicDB、Kvasir、CVC-ColonDB和ETIS-LaribPolypDB上的测试结果表明,文中所提新方法能够取得更好的分割效果,其Dice相似性指数分别为0.946、0.927、0.805和0.781。 展开更多
关键词 结直肠息肉 transformER 相位感知模块 极化自注意力模块
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Theoretical Model of Transformation Superlastic Diffusion Bonding for Eutectoid Steel 被引量:2
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作者 LU Shi-hong, YUN Jun-bi (College of Mechanic and Electricial Engineering, Nanjing University of Aeronautics & Astronautics, Nanjing 210016, China) 《厦门大学学报(自然科学版)》 CAS CSCD 北大核心 2002年第S1期13-14,共2页
Based on current theories of diffusion and creep cavity closure at high temperature, a theoretical analysis of phase transformation diffusion bonding for T8/T8 eutectoid steel is carried out. The diffusion bonding is ... Based on current theories of diffusion and creep cavity closure at high temperature, a theoretical analysis of phase transformation diffusion bonding for T8/T8 eutectoid steel is carried out. The diffusion bonding is mainly described as two-stage process: Ⅰ The interfacial cavity with shape change from diamond to cylinder.Ⅱ The radius of the cylindrical cavity are reduced and eliminated gradually. A new theoretical model is established for the process of transformation superplastic diffusion bonding (TSDB) on the basis of a theoretical model for isothermal superplastic diffusion. The model can predict the bonding quality which is affected by technological parameters, such as limit cycling temperature, the compressive stress, the numbers of thermal cycles and temperature cycling through the phase transformation in the thermal cycling and so on. Results show that the maximum temperature, the compressive stress, the numbers of thermal cycles and the rate of temperature changing speed in the thermal cycling have an important influence on TSDB process. Meanwhile, reasonable technological parameters chosen from theoretical analysis is in good agreement with those obtained from experimental results. 展开更多
关键词 TSDB eutectoid steel phase transformation SUPERPLASTICITY diffusion bonding theoretical model
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Magnetite-Hematite Transformation: Correlation Between Natural and Sintetic Features
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作者 Paola F.Barbosa Leonardo Lagoeiro +1 位作者 Ricardo Scholz Leonardo M.Graa 《矿物学报》 CAS CSCD 北大核心 2013年第S1期72-72,共1页
The iron-oxide system can be used as a marker of oxidized and reduced conditions in closed systems. However, natural rocks with iron-oxide minerals also exhibit such reactions, although the natural system is typically... The iron-oxide system can be used as a marker of oxidized and reduced conditions in closed systems. However, natural rocks with iron-oxide minerals also exhibit such reactions, although the natural system is typically open. To understand the behaviour of this natural system, they were investigated the similarities, in terms of crystallographic textures, between the microstructures of two systems: natural open system and synthetic closed system of iron-oxide phase transformation. 展开更多
关键词 MAGNETITE HEMATITE phase transformation EBSD
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Design and implementation of code acquisition using sparse Fourier transform
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作者 ZHANG Chen WANG Jian +1 位作者 FAN Guangteng TIAN Shiwei 《Journal of Systems Engineering and Electronics》 SCIE CSCD 2024年第5期1063-1072,共10页
Code acquisition is the kernel operation for signal synchronization in the spread-spectrum receiver.To reduce the computational complexity and latency of code acquisition,this paper proposes an efficient scheme employ... Code acquisition is the kernel operation for signal synchronization in the spread-spectrum receiver.To reduce the computational complexity and latency of code acquisition,this paper proposes an efficient scheme employing sparse Fourier transform(SFT)and the relevant hardware architecture for field programmable gate array(FPGA)and application-specific integrated circuit(ASIC)implementation.Efforts are made at both the algorithmic level and the implementation level to enable merged searching of code phase and Doppler frequency without incurring massive hardware expenditure.Compared with the existing code acquisition approaches,it is shown from theoretical analysis and experimental results that the proposed design can shorten processing latency and reduce hardware complexity without degrading the acquisition probability. 展开更多
关键词 code acquisition hardware structure sparse Fourier transform(SFT) code phase estimation Doppler frequency estimation
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Research on Feature Extraction of Composite Pseudocode Phase Modulation-Carrier Frequency Modulation Signal Based on PWD Transform
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作者 李明孜 赵惠昌 《Defence Technology(防务技术)》 SCIE EI CAS 2008年第4期281-284,共4页
The identification features of composite pseudocode phase modulation and carry frequency modulation signal include pseudocode and modulation frequency. In this paper,PWD is used to extract these features. First,the fe... The identification features of composite pseudocode phase modulation and carry frequency modulation signal include pseudocode and modulation frequency. In this paper,PWD is used to extract these features. First,the feature of pseudocode is extracted using the amplitude output of PWD and the correlation filter technology. Then the feature of frequency modulation is extracted by way of PWD analysis on the signal processed by anti-phase operation according to the extracted feature of pseudo code,i.e. position information of changed abruptly point of phase. The simulation result shows that both the features of frequency modulation and phase change position caused by the pseudocode phase modulation can be extracted effectively for SNR=3 dB. 展开更多
关键词 信号接收系统 信号分析 侦察 电子对抗
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激光固态相变贝氏体道岔钢滚动磨损与接触疲劳行为研究
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作者 李鹏 姚鑫宇 +4 位作者 王梁 汪渊 丁昊昊 张群莉 王文健 《表面技术》 北大核心 2025年第17期150-161,共12页
目的 探讨激光固态相变提升贝氏体道岔钢耐磨性能和抗滚动接触疲劳性能的可行性。方法 首先,对贝氏体道岔钢进行激光固态相变处理,分析激光固态相变后贝氏体道岔钢的微观组织和力学性能。然后,利用MJP-30A型滚动接触疲劳试验机开展滚动... 目的 探讨激光固态相变提升贝氏体道岔钢耐磨性能和抗滚动接触疲劳性能的可行性。方法 首先,对贝氏体道岔钢进行激光固态相变处理,分析激光固态相变后贝氏体道岔钢的微观组织和力学性能。然后,利用MJP-30A型滚动接触疲劳试验机开展滚动接触模拟试验,分析激光固态相变对贝氏体道岔钢磨损与接触疲劳演变规律的影响。最后,讨论激光固态相变处理贝氏体道岔钢的滚动接触疲劳损伤机理。结果 经激光固态相变处理后,形成了板条状马氏体为主的相变硬化区和回火马氏体为主的回火软化区,相变硬化区的表面硬度为503HV0.2~549HV0.2,相较于基体提升了14.3%,回火软化区的表面硬度为451HV0.2~482HV0.2,与基体接近。与未处理贝氏体相比,激光固态相变贝氏体的磨损率降低了83.4%,耐磨性显著提升。此外,裂纹扩展结果表明,未处理贝氏体试样以网状损伤为主,激光固态相变贝氏体试样以单条裂纹损伤为主,当裂纹穿过激光固态相变产生的马氏体层到达基体区域时,裂纹发生偏折,以大角度向基体内部扩展。结论 通过激光固态相变可以提升贝氏体道岔钢的耐磨损和抗滚动接触疲劳性能,相变硬化区的抗疲劳性能最优,回火软化区次之,未处理贝氏体试样的抗疲劳性能最差。 展开更多
关键词 贝氏体道岔钢 激光固态相变 相变硬化 回火软化 磨损 接触疲劳
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基于差动电流相位特性的电流互感器中性线异常识别方法
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作者 唐治国 陈琦 +4 位作者 王胜 孙震宇 薛明军 顾剑飞 张少华 《电力自动化设备》 北大核心 2025年第5期136-144,共9页
针对电流互感器中性线异常导致的差动保护在区外故障下的不正确动作问题,提出一种基于差动电流相位的电流互感器中性线异常识别及差动保护策略。对电流互感器中性线异常情况下差动保护区内、外故障下差动电流相位特性及影响因素进行了... 针对电流互感器中性线异常导致的差动保护在区外故障下的不正确动作问题,提出一种基于差动电流相位的电流互感器中性线异常识别及差动保护策略。对电流互感器中性线异常情况下差动保护区内、外故障下差动电流相位特性及影响因素进行了理论分析。根据区内、外故障的故障相与非故障相相位特性差异,提出了一套电流互感器中性线异常识别方法及差动保护策略,解决了现有判据的局限性。利用实时数字仿真系统(RTDS)建立典型的3/2接线母线模型,通过大量仿真实验验证了所提方法的有效性及可靠性。 展开更多
关键词 差动保护 电流互感器 中性线异常 相位特性 继电保护
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