检索结果-南通市图书馆

Evolution of Field Entropy in the Formation of a Photon-Number State

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 1997年第7期14卷 517-520页

作者： liu zheng-dong ZENG Liang Department of Physics Zhejiang UniversityHangzhou 310027

In the formation of a photon-number state in a micromaser,the evolution of field entropy versus the injected atom number is studied with and without the rotating-wave approximation,and the results in these two differe... 详细信息

关键词： entropy rotating oscillation

基于PCA+KNN和kernal-PCA+KNN算法的废旧纺织物鉴别

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

分析测试学报 2024年第7期43卷 1039-1045页

作者：李宁宁刘正东王海滨韩熹李文霞北京服装学院材料设计与工程学院北京100029 北京服装学院服装艺术与工程学院北京100029 即发集团染整厂山东青岛266200 北京伟创英图科技有限公司北京100070

该研究采集了15类废旧纺织物的4 998张近红外谱图,以7∶3的比例分为训练集和验证集,并分别采用主成分分析(PCA)与核主成分分析(kernal-PCA)两种不同降维方法对数据进行降维,并选用余弦相似度(cosine)核作为kernal-PCA的最佳核函数,最后... 详细信息

该研究采集了15类废旧纺织物的4 998张近红外谱图,以7∶3的比例分为训练集和验证集,并分别采用主成分分析(PCA)与核主成分分析(kernal-PCA)两种不同降维方法对数据进行降维,并选用余弦相似度(cosine)核作为kernal-PCA的最佳核函数,最后分别将PCA和kernal-PCA降维处理后的数据进行k-近邻算法(KNN)训练。结果表明,kernal-PCA+KNN的模型准确率(95.17%)优于PCA+KNN模型的准确率(92.34%)。研究表明,kernal-PCA+KNN算法可以实现15类废旧纺织物识别准确率的提升,为废旧纺织物在线近红外自动分拣提供有力的技术支撑。

关键词：废旧纺织物主成分分析(PCA) 核主成分分析(kernel-PCA) k-近邻算法(KNN) 分类识别

维普期刊数据库博看期刊

Absorption-Free Sub-and Super-Luminal Light Propagation via Quantum Interference

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2012年第10期29卷 42-44页

作者： WU Jian-Chun liu zheng-dong zheng Jun Department of Physics Nanchang UniversityNanchang 330031 Engineering Research Center for Nanotechnology Nanchang UniversityNanchang 330047

We investigate the dispersive and absorptive properties of an N-type four-level atomic system in three coherent fields,and consider the susceptibility *** is shown that the group velocity of the probe field exhibits sub-and super-luminal under some conditions,meanwhile the absorption coefficient keeps zero during the occurrence and transition process of sub-and super-luminal pulses.

关键词： susceptibility coherent absorption

Embrittlement Mechanism due to Slow Cooling During Quenching for M152 Martensitic Heat Resistant Steel

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2010年第6期17卷 60-66页

作者： YANG Gang WANG Chang liu Xin-quan liu zheng-dong Central Iron and Steel Research Institute Beijing 100081 China

The mechanism of brittleness of M152 martensitic heat resistant steel due to slow cooling during quenching was experimentally investigated. The mechanical property tests and microstructure observation were conducted by TEM and XRD. The results showed that the presence of irreversible brittleness during slow cooling of quenching for M152 steel is attributed to the continuous M23C6 precipitation along prior austenite grain boundaries and M2C along prior residual austenite film. The residual austenite in the steel was unstable and decomposed after the precipitation of second phase during the process of slow cooling of quenching. The low cooling rate within the temperature range from 820 ℃ to 660 ℃ plays a key role in impact toughness, and the precipitation of second phase in the same temperature range results in irreversible brittleness.

关键词： M152 martensitic heat resistant steel brittleness carbides decomposition residual austenite

Hot Deformation Behavior of a New 9%Cr Heat Resistant Steel G115

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2013年第9期20卷 73-79页

作者： YAN Peng liu zheng-dong liu Wei BAO Han-sheng WENG Yu-qing Key Laboratory of Advanced Material of Ministry of Eclucation of China School of Materials Science and EngineeringTsinghua University Institute for Special Steels China Iron and Steel Research Institute

The hot deformation behavior of a new heat resistant steel Gl15 designed for 650 ℃ ultra-supercritical （USC） power plants was experimentally studied. Hot compression test was carried out in the temperature range of 900-1 200 ℃ and the strain rate range of 0.1-20 s i by using Gleeble 3800 thermal-mechanical simulator, and the corresponding flow curves were obtained. Experimental results show that the flow stress increases with the decrease of deformation temperature and the increase of strain rate. The hot deformation activation energy of G115 steel was determined to be 494 kJ/mol and the constitutive equation was also obtained. For convenience of the practical applica-tion, a good approximate equation was obtained for calculating the peak stress values of Gl15 steel under different deformation conditions. At the strain value of 0.9, natural logarithm of the critical Zener Hollomon parameter Zc of Gl15 steel was determined to be in the scope of 49.67 and 50.65, above which there will be no dynamic recrystalliza-tion （DRX）. And natural logarithm of the critical Zener-Hollomon parameter Zc of Gl15 steel was determined to be in the scopes of 45.58 and 46.27, below which full DRX may occur. Then, the status diagram of dynamic micro structures of G115 steel was established. In addition, the strain rate sensitivity of Gl15 steel is not constant during the test temperature range and it increases linearly from 900 to 1 200 ℃. Therefore, hot deformation at higher tem- peratures would obtain better workability.

关键词： heat resistant steel G115 hot deformation dynamic recrystallization constitutive equation Zener Hol-lomon parameter

Hot Deformation Behavior of GCr15 Steel

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2013年第3期20卷 50-56页

作者： PENG Ning-qi TANG Guang-bo YAO Jun liu zheng-dong Institute for Structural Materials Central Iron and Steel Research Institute

Hot deformation behavior of GCr15（ASTM 52100） steel was investigated using single-hit compression tests on Gleeble-1500 simulator at the temperature range of 850-1 100 ℃ and strain rate range of 0.1-10 *** flow stress constitutive equation of GCr15 steel during hot deformation was determined by stress-strain curves analysis on the basis of the hyperbolic sine *** the models of dynamic recrystallization fraction and dynamic recrystallization grain size of GCr15 steel were established by the measured curves and microstructure observation in different experimental *** mean activation energy and the time exponent of dynamic recrystallization kinetics equation in the range of experimental conditions were determined to be 356.2 kJ/mol and 2.12,***,the flow stress model was also established by the method of allocating flow stress curve with three main stress values,the saturation stress,the steady state stress and the stress when strain is *** flow stress curves predicted by the developed models under different deformation conditions are in good agreements with the measured ones.

关键词： GCr15 steel hot deformation flow stress dynamic recrystallization

Two-Dimensional Atom Localization via Spontaneous Emission in an Inverted-Y System

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2013年第3期30卷 75-77页

作者： WU Jian-Chun liu zheng-dong zheng Jun WANG Hui-Qin Institute of Modern Physics Nanchang UniversityNanchang 330031 Engineering Research Center for Nanotechnology Nanchang UniversityNanchang 330047 Physics Experiment Center Nanchang UniversityNanchang 330031.

We investigate the behavior of two-dimensional atom localization in an inverted-Y system driven by one coherent field and two standing-wave *** position probability distribution of the atom passing through the spatial-position-dependent standing-wave fields can be determined by measuring the spontaneously emitted *** is found that high-precision two-dimensional atom localization can be obtained by choosing appropriate system parameters.

关键词： parameters. system standing

Three-Dimensional Microstructures and Tensile Properties of Pure Iron During Equal Channel Angular Pressing

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2011年第12期18卷 40-44页

作者： YANG Gang YANG Mu-xin liu zheng-dong WANG Chang Central Iron and Steel Research Institute Beijing 100081 China

Commercial pure iron billets having diameter of 60 mm and length of 180 mm were subjected to equal channel angular pressing（ECAP） at 350 ℃ for 1 to 4 passes via route *** evolutions on three planes（X,Y,Z planes） were characterized by optical microscopy and transmission electron microscopy（TEM）.It was found that after four passes an ultrafine microstructure could be formed on the X plane,but a band structure remained on the Z ***,the mechanical properties exhibited apparent dependence on the *** strength in the x and y directions was higher than that in the z *** microstructural refinement and mechanical properties were discussed in terms of experimental results.

关键词： iron ECAP UFG microstructure mechanical property

Aging Precipitates and Strengthening Mechanism of T122 Boiler Steel

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2010年第2期17卷 67-73页

作者： BAO Han-sheng CHENG Shi-chang liu zheng-dong TAN Shu-ping Institute of Structure Materials Central Iron and Steel Research Institute Beijing 100081 China School of Astronautics Harbin Institute of Technology Harbin 150001 Heilongjiang China

T122 steel has been used to produce superheater or reheater of ultra supercritical boilers. With the help of chemical phase extraction and mierostructure characterization, the performance of aging precipitates of T122 steel, such as M23C6 carbide, Laves phase and MX phase was investigated, the strengthening mechanism of the steel was discussed, and the thermal yield stress of lath substructure, dislocations and precipitates of the steel were calculated. It was found that lath substructure and dislocations dominated the strengthening attribution and precipitation hardening went second to the strengthening attribution.

关键词： T122 heat resistant steel strengthening precipitate substructure dislocation