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| 1 | Effects of heat treatment on mechanical properties and microstructure of tungsten fiber reinforced grey cast iron matrix composites显示文摘In this study,grey cast iron matrix composites reinforced by different volume fractions of tungsten fibers(Vr=0.95%,1.90%,2.85%,3.80%)were investigated in as-cast and under the heat treatment temperatures of 1,000℃and 1,100℃.The microstructure and mechanical properties of the composites were analyzed and tested by means of SEM,micro-hardness tester and three-point bend testing.The results show that with increasing of the volume fraction of tungsten fibers,the composites reinforced by the tungsten fiber have higher flexural strength and modulus than that of cast iron without reinforcement,and the flexural strength increases with the increasing of heat treatment temperatures.Due to diffusion reaction between matrix and reinforcing phases,the process of heat treatment,the number of graphite flakes in the matrix seemingly becomes lower;and some hard carbide particles are formed around the residual tungsten fibers.Not only does the hardness of both matrix and reinforcement change tremendously,but also the region of reinforcement is also extended from the original 0.11 mm to 0.19 mm in radius. | Niu Libin Xu Yunhua Peng jianHong Wu Hong | 2009 | China Foundry2009，6，4： | 3 |
| 2 | Study on in-situ WC particles/tungsten wire reinforced iron matrix composites under electromagnetic field显示文摘By applying electromagnetic field to a system consisting of tungsten wires and grey cast iron melt,the grey cast iron matrix composite reinforced by either in-situ WC particles or the combination ofin-situ WC particles and the residual tungsten wire was obtained.By means of differential thermal analysis(DTA),the pouring temperature ofiron melt was determined at 1,573 K.The microstructures of the composites were analyzed by using of X-ray diffraction(XRD),scanning electron microscopy(SEM) equipped with an energy dispersive spectrum(EDS) and pin-on-disc abrasive wear test.The obtained results indicated that,with the enhancing frequency of electromagnetic field,the amount ofin-situ WC particles gradually increases,leading to continuous decrease of the residual tungsten wires.When the electromagnetic field frequency was up to 4 kHz,tungsten wires reacted completely with carbon atoms in grey cast iron melt,forming WC particals.The electromagnetic field appeared to accelerate the elemental diffusion in the melt,to help relatively quick formation of a series of small FeW-C ternary zones and to improve the kinetic condition ofin-situ WC fabrication.As compared with the composite prepared without the electromagnetic field,the composite fabricated at 4 kHz presented good wear resistance. | Niu Libin Xu Yunhua Wu Hong | 2010 | China Foundry2010，7，2： | 2 |
| 3 | RGB WGM lasing woven in fiber braiding cavity显示文摘It is critical to realize woven and wearable red-green-blue(RGB) whispering gallery mode(WGM)lasing that is tunable and flexible in the fiber braiding cavity. However, it is still a challenge to achieve tunable full-color lasing with the large color gamut by a facile approach. Here, we design the braiding cavity to realize RGB WGM lasing with high performance. The braiding cavity consists of three optical fibers coated with dye-doped polymer. Each fiber therein serves as a resonant cavity to support multiple lasing modes. There is no interference owing to the air gap between them;therefore, we can achieve full-color WGM lasing. The lasing emission in our fiber braiding cavity covers a color gamut of 86.7% larger than standard RGB space.Our work may provide a platform for potential applications in white laser and integrated optoelectronic devices. | Kun GE Zhiyang XU Dan GUO Ben NIU Jun RUAN Libin CUI Tianrui ZHAI | 2022 | Science China(Information Sciences)2022，65，8： | 2 |
| 4 | Application of ERA5 Reanalysis to the Construction of Initial Conditions for WACCM Simulations显示文摘This study uses ECMWF fifth-generation reanalysis, ERA5, which extends to the mesopause, to construct the Initial Conditions(IC) for WACCM(Whole Atmosphere Community Climate Model) simulations. Because the biases between ERA5 and Sounding of the Atmosphere using Broadband Emission Radiometry(SABER) temperature data are within ±5 K below the lower mesosphere,ERA5 reanalysis is used to construct IC in the lower atmosphere. Four experiments are performed to simulate a Stratospheric Sudden Warming(SSW) event from 5 to 15 February 2016. The simulation using the WACCM default climatic IC cannot represent the sharp meteorological variation during SSW. In contrast, the 0~4 d forecast results driven by ERA5-constructed IC is consistent with ERA5 reanalysis below the middle mesosphere. Comparing with WACCM climatology ICs scheme, the ICs constructing method based on ERA5 reanalysis can obtain 67%, 40%, 22%, 4% and 6% reduction of temperature forecast RMSE at 10 hPa, 1 hPa, 0.1 hPa, 0.01 hPa and 0.001 hPa respectively. However,such improvement is not shown in the lower thermosphere. | WANG Yegui JING Wenqi CUI Yuanyuan CAI Qifa LAN Weiren FANG Hanxian WENG Libin NIU Jun | 2018 | 空间科学学报2018，38，4： | 1 |
| 5 | Preparation of in situ-formed WC/Fe composite on gray cast iron substrate by a centrifugal casting process显示文摘 | Libin Niu Mirabbos Hojamberdiev Yunhua Xu | 2010 | Journal of Materials Processing Tech2010，，14： | 1 |
| 6 | Establishment of N_mF_2 empirical model in the northern hemisphere based on COSMIC occultation data显示文摘Ionospheric peak value of F2 layer(Nm F2)is an important parameter in the ionosphere,which has important applications in short-wave communication,ionospheric modeling and so on.In this paper,the empirical orthogonal function(EOF)decomposition method is used to analyze the Nm F2obtained from the occultation data.Daily spatial distribution of Nm F2at the same time is relatively even.Variance of first modal is much larger than the other modals.A local wavelet power spectrum(LWPS)method is applied to analysis the cycle of F10.7index and time coefficient of first modal.The result shows that they have similar cycle distribution,indicating that F10.7index is the main factor affecting variation of Nm F2.A function is established between the tine coefficient of first modal and F10.7index,average F10.7index value of early 81 days fp by least squares method.The results show that contribution coefficient of fp is negative which indicates that fp has an inert effect existing in the ionosphere.Contribution coefficient of F10.7is positive,which is consistent with the fact that it has an anomaly in winter/spring seasons.In summary,it is feasible to establish a mid-latitude empirical Nm F2model in northern hemisphere based on occultation data and EOF decomposition method. | NIU Jun FANG HanXian WENG LiBin | 2014 | Science China(Technological Sciences)2014，57，2： | 1 |
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