波导

The formation mechanism of the absolute instability and gyrotron backward wave oscillations is analyzed, and the methods to suppress the parasitical modes are discussed.The nonlinear theory model of gyro-TWT is consummated by considering the influence of tapered magnetic field and waveguide radius, electron velocity spread, and waveguide loss on electron beam-wave interaction. The large-signal characteristic of gyro-TWT, such as launching loss and absolute instability, are also analyzed in detail. This work establishes the foundation for the development of a gyro-TWT amplifier.

重点研究了两段损耗波导结构和损耗陶瓷结构回旋行波管中的电子注-波互作用，分析了绝对不稳定性和回旋返波振荡的形成机制和抑制寄生模式的方法；完善了回旋行波管的非线性理论模型，并考虑了磁场和波导半径渐变、速度零散、波导损耗等因素对注-波互作用的影响；详细分析了发射损耗、相位稳定性等回旋行波管的大信号特征，为回旋行波管放大器的研制奠定了基础。

The modification occurred in crystal lattice and the restoration effect of annealing are discussed by analyzing the intensity, width and angle of the X-ray diffraction peaks. The H〓 concentration and related structural information are deduced by the evolution of OH〓 absorption spectra with annealing, which offers the experimental proof for further discussion on annealing. The disappearance of the OH〓 absorption peak at 3300cm〓 after annealing indicates that some H〓 of high concentration diffused further into the substrate and the crystal phase changes accordingly.

根据质子交换波导退火前后在OH〓吸收峰特征的变化，推断波导层H〓浓度及相关的结构信息，并对进一步分析退火机制提供了实验依据；由于3300cm〓〓处的吸收峰代表的是立方钙钛矿的HNbO〓结构成分，因此退火后该峰的消失确实说明高浓度区域的H〓继续向波导深度迁移的事实，同时波导区的晶相成分也发生变化。

Finally, applications of the anomalous propagation of microwave in tropospheric ducts are discussed: in connection with concrete radar parameters, effects of ducts on radar range and detection performance are discussed, the results obtained are of great value for the overall design of radar systems; by use of the interference standards of ITU-R, the co-ordination area of satellite earth-station under tropospheric ducts environment is studied ; by explaining the relationship between evaporation duct and advection fog, a new way to forecast sea advection fog from evaporation duct is provided.

最后讨论了对流层大气波导环境下电波异常传播特性的应用：结合具体的雷达系统参数，模拟计算了大气波导对雷达作用距离及发现概率的影响，对雷达系统的总体设计具有重要的参考价值；对表面大气波导环境下的卫星地球站通信协调区域进行了确定，从理论上很好地给出了协调距离量级的概念，为卫星地球站与地面微波站之间的协调提供了依据和参考；分析了利用海面蒸发波导来快速预测平流海雾的新方法，完善了平流海雾的预报方法，对海上安全作业和生产具有重要的意义。

SH guided wave dispersion characteristics and wave structure for free surface isotropic elastic pipe circumferential waveguide were calculated and analyzed to guide pipeline inspection,and these characteristics were compared with those of the plate SH guided wave.

为指导基于超声导波的管道无损检测，计算并分析水平切变（shear horizontal，SH）导波在具有自由内表面、外表面的弹性各向同性管道周向波导中传播的频散和波结构特性，将这些特性与平板SH导波的对应特性进行对比分析。

Initial numerical results indicate that the pentagonal waveguide proposed have more power carrying capability and higher power capacity than rectangular and elliptical ones.

初步的数值分析表明：与目前常用的高功率波导——矩形波导和椭圆波导相比，五边形波导具有更强的功率携带能力和更大的功率容量，因而具有很大的实用价值。

Based on orthogonal function unfolding theory, the transverse fields can be represented as a superposition of waveguide modes. And according to coupled-wave theory, the time-dependent multi-mode coupling-wave equations (or the generalized telegrapher's equations) and the coupling coefficients among the different modes were deduced. The generalized telegrapher's equations are a set of coupled one-dimensional partial differential equations for the amplitudes of the modes.

应用正交函数的展开理论，将变截面波导中的电磁场表示为横电波和横磁波本征模式的级数；然后根据耦合波理论，推导了考虑波导金属壁有限电导率的变截面波导时域多模耦合波方程组及各模式间耦合系数的表达式。

Based on the basic equations of electromagnetic waves transmit in waveguide, then focus on three different geometric border waveguide (rectangular, deltaic, cylindrical) for discussion ,the basic equations of electromagnetic waves in rectangular waveguide , deltaic waveguide and cylindrical waveguide are got.

本文在得出求波导中电磁波的基本方程后，针对三种不同几何边界的波导管进行讨论，导出了电磁波在矩形波导、三角形波导和圆形截面的空心波导中传播的基本方程。

When the output branch number is more than 2, we can construct a cascade connection of Y-branch waveguides. However, it occupies a large optical circuit area. The power dividers with 2N output branches can be setup by arranging (2N-1) branch waveguide. However, the design of dividing structures with output branches of odd number such as three or five are difficult.

当输出波导数大於2时，可以用串接的方式来增加输出波导数，但是所需空间会变大，而光功率分配器的2N分岔输出是可以由(2N-1)的分岔输出结构改变而来的，所以在设计奇数波导输出像是3或是5的波导数输出结构就成为一个必须的课题。

An approximate analytical approach, which can be used to analyze the optical characteristics of metal-clad step or graded index waveguides in near cutoff, is presented at first. The mode propagation characteristics of metal-clad step index waveguides in near cutoff are comprehensively analyzed.

GaAs/GaAlAs异质结光波导材料是目前集成光学中的重要材料，本论文在系统介绍外延生长技术的基础上，利用普通的液相外延炉，成功地生长出可用于光波导器件制作的、表面较光滑并具有较大面积（14×16mm〓）的GaAs/GaAlAs异质结光波导材料，C-V法测得波导层载流子浓度为2—4×10〓cm〓，Al-Schottky接触的反向电压大于20伏，平板波导和脊波导通光实验良好。

A novel Y branch waveguide structure is presented, in which a transitional guide is embedded between an incident channel and an output branch.

提出了一种新型的Y分支光波导结构。该Y分支波导由一个入射波导、一个过渡波导和一对出射波导组成。

I'm strongly against the death penalty — it's an eye for an eye.

我不赞成死刑——这是以牙还牙的报复行为。

And to get you the support you need, we're enlisting all elements of our national power: our diplomacy and development, our economic might and our moral suasion, so that you and the rest of our military do not bear the burden of our security alone.

并给你们所须的支援，我们正徵召国家所有各种的力量：我们的外交及发展，我们的经济力量与道德劝说，所以你们与其他军人不须要孤独地负起国家安全的责任。