左手材料阶跃型光纤的模场特性

从Maxwell方程组出发,讨论纤芯为左手材料,包层为右手材料阶跃型光纤,推导了矢量解的场方程.经过数学计算,求得了左手材料阶跃型光纤矢量解的特征方程.根据矢量模的分类,找到了TE模、TM模、HE模和EH模的特征方程.根据各模的特征方程,并且与右手材料光纤相关的特征方程,在靠近截止和远离截止两种情况下进行了比较,得到了左手材料光纤的某些奇异特性.

机器学习预测多折射率层有源光纤的模场特性

高功率光纤激光是当前我国激光科学技术领域的前沿热点,而稀土掺杂的有源光纤是高功率光纤激光器的核心器件。与常规有源光纤不同,多折射率层有源光纤的纤芯和包层之间增加了一个或多个辅助折射率层,展现出了特殊的模场特性,有望进一步提升高功率光纤激光的输出功率。利用传统方法分析不同结构参数下多折射率层有源光纤的模场特性时,通常需要耗费较长的时间求解麦克斯韦方程组。笔者首次引入机器学习算法来预测多折射率层有源光纤的模场特性。该方法仅需要数据空间中0.1%的样本,就可以学习多折射率层有源光纤结构参数与其模场特性之间的复杂映射关系,进而实现无须求解麦克斯韦方程组的快速精准预测。该方法的平均预测误差小于0.6%,预测速度相比传统方法提升了约7000倍,为多折射率层有源光纤的模场特性分析提供了新思路。

温度对不同孔形液晶光子晶体光纤的传输特性研究

提出一种可填充E7型液晶的不同孔形光子晶体光纤。基于现有Comsol Muhiphysics软件对不同温度时的光子晶体光纤在同一波长传输特性的影响,从而实现温度变化对填充液晶的不同孔形光子晶体光纤的模场特性规律,得出基膜有效折射率、数值孔径随温度变化快的圆形空气孔是表现光子晶体光纤传输特性的最佳孔形。分析波导色散随入射波长变化的影响,为更好地调制光子晶体光纤器件提供理论依据。

两层镀膜长周期光纤光栅传感器的特性研究

以光纤光栅耦合模理论为基础,提出一种两层镀膜长周期光纤光栅传感器的结构模型,一层是在光纤包层外镀的铜金属薄膜,另一层是在铜薄膜外再镀一层敏感薄膜。对该结构模型的模场特性和透射特性进行分析和模拟,明确了薄膜参数对其透射特性的影响。该结构模型既可以利用敏感膜折射率随外界环境变化而改变的特性,也可以利用金属膜层进行温度和应变调节来改变谐振波长的特点,为高灵敏度长周期光纤光栅传感器的优化设计提供了理论依据。

电磁测试用暗室与半暗室的时域建模、表征与测量

介绍了用于数字化设备发射、抗扰度测试的暗室和半暗室基于时域技术的建模、表征以及测量。针对暗室和半暗室利用时域有限差分（FDTD）法的建模与表征。在提供的FDTD模型中，讨论了不考虑吸波材料空间分布的计算方法；提出了差分计算法，将频率相关的电容率与磁导率集成到时域；还讨论了铁氧体片吸收器上的缝隙、开孔对吸波材料与暗室工作性能的影响。对于不同尺寸的暗室，给出了FDTD模型结果与测试结果的比较。最后，讨论并以实例阐明了怎样用时域方法表征暗室、预测性能、诊断吸波材料与暗室的问题。采用时域与频域方法，描述了如何仅对吸波结构座进行很小改动而获得暗室性能显著提高的方法，另外也说明了在采用性能不太好的吸波材料时暗室内会出现不太理想的场分布特性。

Physically based analytical model for plateau in gate C-V characteristics of strained silicon pMOSFET

A physically based analytical model was developed to predict the performance of the plateau observed in the gate C-V characteristics of strained-Si/SiGe pMOSFET.Experimental results were used to validate this model.The extracted parameters from our model were tOX=20 nm,ND=1×1016cm 3,tSSi=13.2 nm,consistent with the experimental values.The results show that the simulation results agree with experimental data well.It is found that the plateau can be strongly affected by doping concentration,strained-Si layer thickness and mass fraction of Ge in the SiGe layer.The model has been implemented in the software for strained silicon MOSFET parameter extraction,and has great value in the design of the strained-Si/SiGe devices.

Characteristics of gas explosion flow fields in complex pipelines

The explosion flow field in five straight pipes with different diameters and one bending pipe selected from a domestic coal mine are studied by the method of numerical simulation. And the results show that,both in the straight and bending pipes, the pressure wave and velocity wave are accelerated by the rising of reaction rate. As the explosion progressed, with the temperature reaching approximately 3000 K, only one pressure wave and one reaction rate wave were observed, while several velocity waves were found.The larger diameter presented the highest relative pressure as well as the largest velocity increase and subsequent decrease inside the tube. The bent pipes caused both turbulence and kinetic energy to increase, resulting in the acceleration of the reaction rate. The burning time was 7.4% shorter than the burning time observed for the straight pipe. Based on these results, designing one explosion resistance device, and in the practical engineering applications, it was to be proved to meet the security requirements fully.

NUMERICAL SIMULATION OF THE STRUCTURAL STRESS FIELD OF BEIYA GOLD DEPOSIT

Based on the study about the geological background of Beiya Gold Deposit, numerical simulation was conducted about the three-dimensional structural stress field for Beiya Gold Deposit by applying finite element theory and by employing a linear elasticity model. Results of the simulation indicate that the Beiya syncline is a faulted basin, and a hidden fracture occurs in the west wing of the syncline.Under the action of the EW-trending compressive force, four nearly NS-trending fractures (groups) were generated in the stress stretching areas of the two wings of the syncline, and these fractures constitute favorable tectonic positions for the upward intrusion of porphyry magma and the occurrence of Au-Pb-Zn polymetallic deposits.

Effect of Product Differemiation on Business Model Performance in B2B Market

Focusing on B2B market, this paper studies the effect of product differentiation on business model perlbrmance. After interviewing several experts and analyzing numbers of distributing questionnaires. the author discovered that product differentiation has a positive effect on business model performance. Through SEM. it is revealed that product differentiation at each level have positive effect on business model, with different effect weight. The main contributions of this research are summarized as follows： Firstly, the proposed model of the product differentiation on business model performance lays the basis for scientific measurement of product differentiation and its effect on business model performance; Secondly, this research ranks the importance of product differentiation at different level in B2B market; Finally, this research provides a good reference for enterprises to update their product strategy for better business model performance.

阵列波导光栅线性系统理论分析及优化设计

运用线性系统理论分析了阵列波导光栅的模场特性 ,导出器件传输的数学模型即光栅方程。提出了设计阵列波导光栅阵列波导数M的新方法 ,该方法综合考虑了降低器件串扰以及收集发散光场的能力 ,与文献 [1 ]的方法相比简单且准确。分析了造成器件衍射损耗的原因 ,提出了降低器件衍射损耗的方法。给出了 8× 0 .8nm ,中心波长为 1 550nm的阵列波导光栅波分复用器的设计实例 ,并进行了数值模拟计算验证了文中所提方法的准确性。

Uniform arrays of carbon nanotubes applied in the field emission devices

Carbon nanotubes(CNTs)were grown into anodic aluminum oxide(AAO)channels by chemical vapor deposition(CVD)using C2H2/N2mixtures as feeding gas,which can be used as field emitters.The bottom surface of AAO template was etched slightly and the tips of CNTs were explored as the field emission arrays which were uniform and vertical.Field emission characterization showed a low turn-on field about 3.25 V/m and high emission current about 30 mA/cm2with the electric field about 4 V/m.These superior field emission characteristics could be attributed to low density of vertical CNTs and higher conductivity of the substrate.

Potential application of FoldX force field based protein modeling in zinc finger nucleases design

Engineered sequence-specific zinc finger nucleases (ZFNs) make the highly efficient modification of eukaryotic genomes possible.However,most current strategies for developing zinc finger nucleases with customized sequence specificities require the construction of numerous tandem arrays of zinc finger proteins (ZFPs),and subsequent largescale in vitro validation of their DNA binding affinities and specificities via bacterial selection.The labor and expertise required in this complex process limits the broad adoption of ZFN technology.An effective computational assisted design strategy will lower the complexity of the production of a pair of functional ZFNs.Here we used the FoldX force field to build 3D models of 420 ZFP-DNA complexes based on zinc finger arrays developed by the Zinc Finger Consortium using OPEN (oligomerized pool engineering).Using nonlinear and linear regression analysis,we found that the calculated protein-DNA binding energy in a modeled ZFP-DNA complex strongly correlates to the failure rate of the zinc finger array to show significant ZFN activity in human cells.In our models,less than 5% of the three-finger arrays with calculated protein-DNA binding energies lower than 13.132 kcal mol 1 fail to form active ZFNs in human cells.By contrast,for arrays with calculated protein-DNA binding energies higher than 5 kcal mol 1,as many as 40% lacked ZFN activity in human cells.Therefore,we suggest that the FoldX force field can be useful in reducing the failure rate and increasing efficiency in the design of ZFNs.

Supersonic Cavity Based Combustion with Kerosene/Hydrogen Fuel

A comparative study with kerosene and hydrogen fuel in a model scramjet combustor has been carried out nu- merically. The effect of fuel-air equivalence ratio on the flow field properties in a cavity based mixing mechanism at a freestream Math number of 2.08 has been probed. The investigation has been carried out in a two dimension- al numerical model where a cavity of length to depth ratio of 2 is mounted on one of the walls of the flow channel The flow field shock structure is observed to change with the change in fuel-air equivalence ratio. Total pressure loss is observed to depend both on fuel air equivalence ratio and the fuel type. The spread of fuel in the test sec- tion shows marked variation with the equivalence ratio. Performance of injector location on the fuel-air mixing is also probed during the course of the investigation.