The solution of the characteristic equation of circular-rectangular groove guide

Circular-rectangular groove guide is a new type of structure we have presented for coupling between circular groove guide and rectangular groove guide. In this paper, as the continuity of our previous work, the characteristic equation of circular-rectangular groove guide has been solved and the numerical results have been given and discussed.The Project Supported by National Natural Science Foundation of P. R. China     

ISG-FHEV等效燃油消耗最小控制策略

针对室内复杂环境下火灾识别准确率会降低的问题,提出了一种改进的粒子群算法优化支持向量机参数进行火灾火焰识别的方法。首先在 颜色空间进行火焰图像分割,对获得的火焰图像进行预处理并提取相关特征量;其次采用PSO算法搜索SVM的最优核参数和惩罚因子,并在PSO算法中加入变异操作和非线性动态调整惯性权值的方法,加快了搜索SVM最优参数的精度和速度;然后将提取的火焰各个特征量作为训练样本输入SVM模型进行训练,并建立参数优化后的SVM分类器模型;最后将待测试样本输入SVM模型进行分类识别。算法的火灾识别准确率达到94.09%,分类效果明显优于其他分类算法。仿真结果表明,改进的PSO优化SVM算法提高了火焰识别的准确率和实时性,算法的自适应性更强,误判率更低。     

双程掺镱光纤放大器的增益特征及优化

比较了掺钕光纤和掺镱光纤对1064 nm光放大的特点.基于速率方程和传输方程,数值分析了在915 nm泵浦下双程掺镱光纤放大器的增益特征,并且和传统的单程放大进行了比较.分析了信号光和泵浦光,以及粒子数沿着光纤方向的分布特点.最后对双程掺镱光纤放大器进行了优化.     

A Dual-Wavelength Cladding-Pumped Er^3＋/Yb^3＋ Codoped Fibre Laser System with More Than 2 W Output and Tunable Wavelength Spacing

A dual-wavelength laser system with wideband tunable wavelength spacing and more than 2 W output power is proposed and demonstrated. The operation principle of the laser system is based on the saturation gain characteristic of a cladding-pumped Era＋ /yba＋ co-doped fibre amplifier combining with a wideband tunable fibre laser with fiat power spectrum. The tuning range of the wavelength spacing is continuous within a 35 nm spectral range, and the power difference between both lasing wavelengths can be easily adjusted and controlled by a variable optical attenuator. The total output power can approximately keep unchangeable when the wavelength spacing and the power difference between both lasing wavelengths are continuously tuned and changed. The maximum total output power of the laser system is about 2.22 W.     

Bursting and spiking due to additional direct and stochastic currents in neuron models

Neurons at rest can exhibit diverse firing activities patterns in response to various external deterministic and random stimuli, especially additional currents. In this paper, neuronal firing patterns from bursting to spiking, induced by additional direct and stochastic currents, are explored in rest states corresponding to two values of the parameter $V_{\rm K}$ in the Chay neuron system. Three cases are considered by numerical simulation and fast/slow dynamic analysis, in which only the direct current or the stochastic current exists, or the direct and stochastic currents coexist. Meanwhile, several important bursting patterns in neuronal experiments, such as the period-1 ``circle/homoclinic" bursting and the integer multiple ``fold/homoclinic" bursting with one spike per burst, as well as the transition from integer multiple bursting to period-1 ``circle/homoclinic" bursting and that from stochastic ``Hopf/homoclinic" bursting to ``Hopf/homoclinic" bursting, are investigated in detail.     

Optical low-coherence reflectometry with resolution beyond the Fourier transform limit

We demonstrate experimentally and theoretically a method for enhancing the axial resolution of optical low-coherence reflectometry (OLCR) beyond the Fourier transform limit of light source spectrum. The resolution enhancement originates from the superposition of multiple OLCR scans with different offsets of the center-wavelength light-ray with respect to the rotation axis of the mirror mounted on the galvanometer optical scanner in the used optical phase delay line. After certain software process of the multiple scan fringe patterns of different offsets, the superposition leads to an OLCR axial resolution beyond the transform limit. Experimentally, by using four different offsets for superposition, about 1.5 times enhancement of the transform-limit resolution is obtained.     

Fabrication of a curved linear grating by using a laser direct writer system

We present the lithography technique to fabricate a curved linear grating by using a Cartesian coordinates laser direct writer (LDW) system. The grating with the period of 15 μm is made on the convex lens surface. This is a new application of the LDW system. After the chromium coating and the photoresist removing procedures, a convex reflecting grating is obtained.     

Studies on Fast Algorithm for the Scattering of a Large Array of Waveguide-Fed Wide-Slot Antennas in Millimeter Wave Region

We present an effective numerical technique to characterize the scattering of wide-slot antennas fed by waveguides with arbitrary terminations in terms of the method of moment (MoM) and the mixed potential integral equation (MPIE). In particular, the precorrected-fast Fourier transform (P-FFT) eliminates the need to generate and store the usual square impedance matrix andthus leads to speed up the matrix-vector multiplication in the resultant system. This property makes the Rao-Wilton-Glisson (RWG) functions to be useful in simulating electrically large-scale problems. In addition, the scattering from the finite ground surfaces is accounted for in the total scattered field by using the method of equivalent edge currents. The numerical results are presented and compared with both the traditional method of moment results obtained using the entire-domain basis functions and the experimental results, to demonstrate the proposed method to be a good candidate for study on the scattering of arbitrary wide-slot large array.