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Search Results: 1 - 10 of 11361 matches for " Fengfei Xing "
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Double Cladding Seven-core Photonic Crystal Fiber  [PDF]
Gelin Zhang, Fengfei Xing, Peiguang Yan, Huifeng Wei, Huiquan Li, Shisheng Huang, Rongyong Lin, Kangkang Chen
Optics and Photonics Journal (OPJ) , 2013, DOI: 10.4236/opj.2013.32B011

A double cladding seven-core PCF was presented for high power supercontinuum generation. The calculated zero dispersion wavelength is located at 912 nm, which has a good agreement with the measurement. The attenuation is measured 6 dB/km at 1590 nm and lower than 14.5 dB/km at 1060 nm, the water-loss peak at 1380 nm is about 134 dB/km; Supercontinuum spanning over more than 1500 nm was generated when the designed seven-core PCF was pumped by a gain-switching Yetterbium-doped fiber laser. These results will be helpful in the future design of multicore photonic crystal fibers (MCPCF) with proper guidance properties for high power supercontinuum generation.

Study on the Implementation of Green Supply Chain Management in Textile Enterprises
Fengfei Zhou
Journal of Sustainable Development , 2009, DOI: 10.5539/jsd.v2n1p75
Abstract: The green supply chain management is a sort of modern management mode which could comprehensively consider the environmental influence and resource utilization efficiency in the whole supply chain and how to implement the green supply chain management in special industrial operation at present has become into one of hotspot problems. This article mainly studied the core contents that textile and apparel enterprises implemented green supply chain management.
Positive Solutions of Singular Initial-Boundary Value Problems to Second-Order Functional Differential Equations
Fengfei Jin,Baoqiang Yan
Boundary Value Problems , 2008, DOI: 10.1155/2008/457028
Abstract: Positive solutions to the singular initial-boundary value problems x ¢ € 2 ¢ € 2= ¢ ’f(t, ¢ € ‰xt), ¢ € ‰0 Keywords
Positive Solutions of Singular Initial-Boundary Value Problems to Second-Order Functional Differential Equations
Jin Fengfei,Yan Baoqiang
Boundary Value Problems , 2008,
Abstract: Positive solutions to the singular initial-boundary value problems are obtained by applying the Schauder fixed-point theorem, where on and may be singular at and . As an application, an example is given to demonstrate our result.
Fabrication of Si-PDMS Low Voltage Capillary Electrophoresis Chip  [PDF]
Wenwen GU, Zhiyu WEN, Zhongquan WEN, Yi XU, Fengfei LIANG, Xiaoguo HU
Engineering (ENG) , 2009, DOI: 10.4236/eng.2009.12013
Abstract: This paper discusses the fabrication of Si-PDMS low voltage capillary electrophoresis chip (CE chip). Arrayed-electrode which is used to apply low separation voltage is fabricated along the sidewalls of the separation channel on the silicon based bottom part. Isolation trenches, which are placed surrounding the arrayed-electrode, insure the insulation between the arrayed-electrode, as well as arrayed-electrode and liquid in the micro channel. Polydimethylsilicone (PDMS) is used as the cover. PDMS and silicon based bottom part are reversible sealed to attain Si-PDMS low voltage CE chip. Experiments have been done to obtain optimum electrophoresis separation condition: separation voltage is 45V, switch time is 2s and the Phe and Lys electrophoresis separation is successful.
Surface configurations during annealing of sputter-deposited NiTi thin films
Gong Fengfei,Jiang Enyong,Shen Huimin,Wang Yening
Chinese Science Bulletin , 1997, DOI: 10.1007/BF02883211
Reliability of the 20CR Reanalysis Data in Measuring the East Asian Summer Monsoon Variability

SONG Fengfei,ZHOU Tianjun,

大气科学 , 2012,
Abstract: This study evaluates the performance of the recently released 20th Century Reanalysis (20CR) data in describing East Asian summer monsoon (EASM) variability by contrasting the results with NCEP1 and ERA40 reanalysis and instrumental datasets. This analysis focuses on the climatology, interannual variability, and decadal change of the EASM. The results show that the 20CR reanalysis data reasonably depicts the high- and low-level circulation fields, including the South Asian high, subtropical jet, and near surface wind, and the meridional monsoon circulation cell. However, in comparison with NCEP1 and ERA40, 20CR data shows a stronger South Asian high, more northward displacement of the subtropical jet, and systematically warmer air temperature in the mid- and high-troposphere. The three reanalysis datasets are highly consistent in measuring EASM variability with the exception of the period before 1967, during which interannual variability results differ due to biases in NCEP1. The monsoon indices based on zonal wind shows better consistency than those based on meridional wind, and the monsoon index based on low-level zonal wind shows the best consistency among the three datasets. 20CR reasonably reproduces interannual variability of the surface air temperature and precipitation related to the EASM, which has a westward and strongest positive correlation center and a weak negative correlation center near Hetao Plain. In addition, precipitation in the Bay of Bengal and along the Yangtze River valley is represented more accurately in the 20CR dataset than that in the other two reanalysis datasets; however, results are opposite in the tropical regions and the oceans. At the interdecadal time scale, however, the 20CR reanalysis data failed to reproduce decadal weakening of the EASM circulation, which is also reflected in its failure to reproduce the observed southern China flood and northern China draught rainfall pattern and surface cooling trend downstream of the Tibetan Plateau. These results are mainly attributed to the deficiency of 20CR reanalysis data in measuring the upper tropospheric cooling tendency over East Asia. During the past 100 years, 20CR has shown consistency in EASM changes with that of observation; this dataset has reasonably depicted the notable cold period before the 1920s and the rapid warming period after the 1990s but has shown weaker skills in presenting the relatively warm period during the 1920s-1950s and the relative cold period during the 1950s-1980s in the EASM region.
Fundamental Diagram of Pedestrian Dynamics by Safety Interspace Model
Jun Fang,Zheng Qin,Zhengcai Lu,Fengfei Zhao
Physics , 2012,
Abstract: The NaSch model is a classical one-dimensional cellular automata (CA) model of freeway traffic. However, it is not suitable for simulating pedestrian dynamics due to the kinetic difference between vehicles and pedestrians. Based on NaSch model, we proposed a new safety interspace model to investigate the single-file pedestrian stream. We simulated and reproduced Seyfried's experiment in 2006 quantitatively and use the empirical data to validate our model. We defined the safety interspace as a linear function of current velocity and introduced a normal distributed random variable to describe the randomness of spatial cognition. Meanwhile, we extended NaSch model in space partition from single-grid mode to multi-gird mode to increase spatial resolution. It was found that through three model perimeters with appropriate values, the new model could reproduce faithfully the typical form of the fundamental diagram from empirical data. The velocity-density curve in simulation could indicate the discontinuity areas in fundamental diagram observed from empirical data. In addition, we reproduced the stop-and-go waves and phase separation into a stopping area and an area where pedestrians walk slowly at high density.
宋丰飞 SONG Fengfei,周天军 ZHOU Tianjun
大气科学 , 2012, DOI: 10.3878/j.issn.1006-9895.2012.12005
Abstract: 本文利用NCEP1和ERA40再分析资料,并结合观测资料,对最新公布的一套再分析资料——20CR再分析资料在东亚夏季风区的质量进行了综合评估。本文主要是从气候态、年际变率、年代际变化三个方面,来评估20CR再分析资料在东亚夏季风区的质量。结果表明,在气候平均态上,20CR再分析资料基本合理再现了东亚夏季风区的高低层环流场(包括南亚高压、副热带西风急流、近地层风场)以及经向环流圈特征。但相较于NCEP1和ERA40,20CR所刻画的南亚高压偏强,西风急流偏北,对流层中上层温度系统性偏高。在年际变率方面,除了NCEP1在1967年之前存在偏差,使其结果和ERA40、20CR不同之外,三套再分析资料刻画的东亚夏季风变率在其它时段高度一致。三套资料在以纬向风为基础的东亚夏季风指数上的一致性,高于以经向风为基础的东亚夏季风指数,其中以低层纬向风为基础的东亚夏季风指数的一致性最高。20CR再分析资料可以较好地再现与东亚夏季风相联系的地表气温和降水年际变化特征,其刻画的地表气温正相关中心位置偏西、强度最强,且在河套平原地区有一个弱的负相关中心,而其描述的降水在孟加拉湾和长江流域较之另外两套再分析资料更接近观测结果,在热带地区和海上却反之。在年代际变化方面,20CR再分析资料未能合理再现东亚夏季风年代际减弱的现象,这也体现在不能合理再现青藏高原下游年代际变冷和“南涝北旱”降水型上,这主要是因为20CR再分析资料所刻画的东亚地区对流层中上层年代际变冷信号偏弱所致。而在百年时间尺度上,20CR再分析资料所刻画的东亚夏季风变化与观测较为一致;20CR再分析资料可以合理再现出东亚夏季风区1920年代前的显著冷期和1990年代之后的迅速增暖期,但对1920~1950年代相对暖期和1950~1980年代相对冷期的再现能力较差。
Two Modified QUICK Schemes for Advection-Diffusion Equation of Pollutants on Unstructured Grids  [PDF]
Linghang XING
Journal of Water Resource and Protection (JWARP) , 2009, DOI: 10.4236/jwarp.2009.15043
Abstract: In this paper, two modified QUICK schemes, namely Q-QUICK and UQ-QUICK, for improving the preci-sion of convective flux approximation are verified in advection-diffusion equation of pollutants on unstruc-tured grids. The constructed auxiliary nodes for Q-QUICK/UQ-QUICK are composed of two neighboring nodes plus the next upwind node, the later node is generated from intersection of the line of current neighboring nodes and their corresponding interfaces. 2D unsteady advection-diffusion equation of pollut-ants is conducted for their verifications on unstructured grids. The numerical results show that Q-QUICK and UQ-QUICK have similar computational accuracy to the central difference scheme and similar numerical stability to upwind difference scheme after applying the deferred correction method. In addition, their corre-sponding CPU times are approximately equivalent to those of traditional difference schemes and their abili-ties for adapting high grid deformation are robust.
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