结构稳定性

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。

Therefore, the interaction structures with distributed wall losses and attenuating severs were more stability for absolute instability and gyrotron backward oscillations.

藉由引用非线性程式进行磁旋行波放大器稳定分析，结果显示散布式损耗(distributed-losses)的设计对绝对不稳定有明显的抑制作用，而隔离管结构亦具有减短磁旋返波振荡作用长度的效用，因此我们采用兼具隔离管及散布式损耗结构的磁旋行波放大器，同时提升绝对不稳定和磁旋返波振荡的稳定性。

In addition, different reaction parameters have been further studied on the synthesis of cubic mesoporous silica.

这种立方介观结构的磷酸氧锆介观结构材料具有很高的热稳定性。

Based on the demands for leakage harness of tailing dam in copper mine,three aspects of acid-resistant reliability, anti-seepage grade and curtain integrality were described to the required characteristics of anti-seepage curtain constructed in tailing dam.

为满足矿山尾矿坝的渗漏治理，从抗酸稳定性、防渗等级和帷幕完整性三个方面阐述了尾矿坝防渗帷幕的性能要求，基于矿物晶体结构的理论分析和对纯水与酸性渗透液的对比试验，分析了粘土固化浆液的抗酸稳定性，研究了粘土固化注浆帷幕的防渗特性，并结合工程实例，介绍了尾矿坝基础防渗中粘土固化注浆帷幕的设计、施工工艺和质量控制措施。

Cyclodextrins, cyclic oligosaccharides commonly composed of six, seven or eight respectively D-glucopyranosyl units connected by α-(1, 4)-glycosidic linkages, have the ability to form inclusion complexes with a wide range of substrates for their particular structures. With proper rigidity and flexibility, excellent mechanical stability and biocompatibility, cyclodextrins are good choice of material in molecular imprinting technology.

环糊精是由六，七或八个D-吡喃葡萄糖单元通过α-1，4 糖苷键连接成的环状低聚糖，由于其特殊的结构使其可以包结一系列的底物，加之具有适当的刚性、柔性、机械稳定性，良好的热稳定性和生物相容性等使其成为分子印迹技术优秀的选择材料。

Firstly, based on the sliding mode control and backstepping technique, a new attitude tracking controller is derived to control the attitude motion of spacecraft, the stability of the system is analyzed via Lyapunov method and the reaction wheel dynamics is also considered from the real applications point of view. The whole design process is divided into two steps: the first step is to use sliding control technique to design suppositional adaptive variable structure controller; and the second step is to design attitude tracking controller based on SMC and backstepping technique. Numerical simulations are performed to show that both tracking maneuver and vibration suppression can be accomplished effectively.

首先，采用自适应后步法结合主动振动控制技术设计了姿态跟踪鲁棒控制器，基于Lyapunov方法分析了系统的渐近稳定性；在此基础上，显性地考虑了执行机构动态特性问题，将整个设计过程分为两个步骤：第一步采用滑模控制技术设计了变结构虚拟控制器，给出自适应控制律的设计方法；第二步，将后步法与滑模控制技术相结合，设计了姿态跟踪鲁棒控制器，给出飞轮电压的输入算法及稳定性分析；最后，将提出的控制方法应用于挠性航天器的姿态跟踪控制，通过数值仿真对所提方法的可行性与有效性进行分析和验证。

From the discussed results above, the six-legged vehicle is considered as a proper selection. In the paper, the stability of legged vehicle while walking on a slope has systemically been analyzed and a formula of the stability of legged vehicle which walks in any direction on a slope has been obtained.

本文对步行车辆在坡道上行走时的稳定性进行了系统分析，得出了步行车辆在坡道上沿任意方向行走时，车辆稳定性的计算方法，提出了步行车辆在结构参数一定时，能够在坡道上沿任意方向稳定行走的最大坡道角的计算方法。

Its Nonlinearity holds at 160 degree C, it is one of the materials that have the best thermal stability. 3. polarization inversion films that consist of melamine formaldehyde resin and polymer/silica hybrid material were fabricated, a simulation model for calculating frequency doubling from multi-layer waveguides was established.

是迄今为止所发现的热稳定性最好的光学基质材料之一。3、利用密胺材料和聚合物/氧化硅复合材料最佳极化温度的差异，制备出重复性好、有较好热稳定性的极性翻转薄膜，并建立了多层波导结构光倍频计算模型。

Instable flowing of plastics in extrusion die head often occurs as the sprue in the die head for plastic profiled bar inner rib is designed excessively dependable on experiences.

针对塑料异型材挤出模头内筋流道设计中过多依赖经验，造成模头作业不稳定的状况，提出了稳定性设计问题，并以实例介绍了运用计算机数值模拟技术辅助设计内筋流道结构参数的过程，提供了一个可行的内筋流道稳定性设计方法。

With high specific surface area, ordered pore structure, facilely tailorable pore size, and fine chemical stability and thermostability, Mesoporous molecular sieve MCM-41 has wide application prospects in many fields, such as catalyst chemistry, adsorption and separation.

介孔分子筛 MCM-41 具有比表面积高、孔道结构规则及孔径易调节、化学稳定性和热稳定性好、表面易改性等优点，在催化化学和吸附分离等领域都有很大的潜在应用前景。

This one mode pays close attention to network credence foundation of the businessman very much.

这一模式非常关注商人的网络信用基础。

Cell morphology of bacterial ghost of Pasteurella multocida was observed by scanning electron microscopy and inactivation ratio was estimated by CFU analysi.

扫描电镜观察多杀性巴氏杆菌细菌幽灵和菌落形成单位评价遗传灭活率。