The Ramsey numbers of paths versus wheels

For two given graphs G₁ and G₂, the Ramsey number R(G₁,G₂) is the smallest integer n such that for any graph G of order n, either G contains G₁ or the complement of G contains G₂. Let P_n denote a path of order n and W_m a wheel of order m+1. In this paper, we show that R(P_n,W_m)=2n-1 for m even and n?m-1?3 and R(P_n,W_m)=3n-2 for m odd and n?m-1?2.     

Nonlinear aerodynamic characteristics and modeling of a quasi-flat plate at torsional vibration: effects of angle of attack and vibration amplitude

Nonlinear Dynamics - The clarification of the nonlinear and unsteady aerodynamic characteristics of a quasi-flat plate is of great importance to predict its wind-induced post-flutter behavior....     

圆极化径向线缝隙天线的设计

在讨论了圆极化径向线缝隙天线形成原理的基础上，完成了该天线的计算机辅助设计和绘图．使用该方法给天线设计带来了方便，能灵活调整缝隙排列、优化排列结构，具有直观和精度高的优点     

Suppression of intra-channel four-wave mixing in 40Gbit/s RZ-DQPSK transmission with alternate-polarization

In this paper, we show that the suppression of intra-channel four-wave mixing (IFWM) in 40 Gbit/s RZ-DQPSK transmission system based on different dispersion maps through using alternate polarization of adjacent symbols. The suppression of IFWM results in significant improvement of system performance. Simulation results show that the amplitude fluctuation is efficiently reduced due to the suppression of the IFWM with alternate-polarization.     

针对X射线双能CT成像的正弦图快速配准方法

双能CI成像技术在医学和安检领域应用广泛,可分为真双能成像和伪双能成像两种类型.针对真双能成像中存在的正弦图空间位置不匹配的问题,提出了一种高低能正弦图快速配准方法.该方法利用相关系数来检测高低能正弦图投影角度方向的相对位移.针对二维相关系数计算量大的问题,采用对正弦图横向左半部分或者右半部分进行横向投影的方法获取一维...     

Electronic compensator for 100-Gb/s PDM-CO-OFDM long-haul transmission systems

We study an electronic compensator (EC) as a receiver for a 100-Gb/s polarization division multiplexing coherent optical orthogonal frequency division multiplexing (PDM-CO-OFDM) system without optical dispersion compensation.EC,including electrical dispersion compensation (EDC),least squares channel estimation and compensation (LSCEC),and phase compensation (PC),is used to compensate for chromatic dispersion (CD),phase noise,polarization mode dispersion (PMD),and channel impairments,respectively.Simulations show that EC is highly effective in compensating for those impairments and that the performance is close to the theoretical limitation of optical signal-to-noise rate (OSNR),CD,and PMD.Its robustness against those transmission impairments and fiber nonlinearity are also systematically studied.     

400 Gbps WDM transmission over short range with discrete multi-tone

We simulate 400 Gbps WDM transmission system with DMT modulation. The system reaches 5 km SSMF with 100 Gbps per wavelength when the BER is 1e−3. From our analyses, we can see that DMT can be a promising solution for high capacity optical transmission system over short distance.     

罗伊氏乳杆菌NCU801对病原菌的粘附抑制性能

采用选择性平板计数法,考察罗伊氏乳杆菌NCU801活菌悬液、死菌悬液以及发酵上清液对大肠杆菌CMCC44496和金黄色葡萄球菌26003粘附Caco-2细胞的影响。结果表明:在竞争试验、排斥试验和置换试验中,罗伊氏乳杆菌NCU801活菌悬液和死菌悬液均能抑制大肠杆菌和金黄色葡萄球菌的粘附;活菌悬液比死菌悬液抑制效果更显著,其中最显著的是活菌悬液对大肠杆菌排斥抑制粘附,粘附抑制率达到(86.8±4.5)%;而发酵上清液在竞争实验中最显著,其次是置换试验,而在排斥实验中对病原菌无影响,说明发酵上清液中的细菌素能够杀死未粘附和已粘附的病原菌。更多还原