集成光芯片的电光性能测试方法

为了提高中低精度光纤陀螺工程化批产过程中的一致性和合格率,降低筛选成本,初步定量研究了铌酸锂集成光芯片的附加损耗、光克尔效应、分光比和偏振效应等重要参数对陀螺性能的影响和优化方法,并提出了电光性能的具体测试方法。通过输入特定方波、锯齿波、方波加阶梯波,可从输出波形上进行直观的判断,并可进一步给出性能优劣的量化指标,能够较为准确地进行芯片筛选,提高工艺水平。此项研究成果对铌酸锂集成光芯片的相关标准进行了补充,不仅可以帮助光纤陀螺的制作单位进行更合理可行的器件筛选,还可以帮助芯片的生产单位完善相应的参数测试工作,提高合格率。     

声表面波（SAW）中陀螺效应的理论研究

本文从定性、定量分析哥氏惯性力对声表面波传播特性的影响，详细推导了声表面波传播速度的改变量与各向同性传播介质旋转角速度的关系．并与光学中的法拉第（Ｆａｒａｄａｙ）效应相比，进一步说明了ＳＡＷ陀螺效应的产生原因。     

闭环光纤陀螺中铌酸锂相位调制器的附加强度调制及其影响

铌酸锂相位调制器是锯齿波调制闭环光纤陀螺的关键器件。本文就钛内扩散铌酸鲤相位调制器及其锯齿波驱动电路不理想而导致的边带抑制进行了理论分析和仿真研究。重点讨论了附加强度调制对边带抑制影响的特点，提出了减小这类误差应采取的技术措施。这为提高闭环光纤陀螺标度因数的线性度提供了理论依据。     

聚变堆相关的液态金属膜流初步实验研究

在磁约束核聚变堆的面对等离子部件设计中,液态金属锂膜流因具有带走杂质、保护面对等离子固壁等优点而被认为是优选方案之一.然而,如何克服聚变堆中强磁场环境下产生的磁流体力学效应并形成大面积均匀铺展锂膜流动是目前亟需解决的问题.本文通过搭建室温液态镓铟锡回路和高温液态锂回路,开展了两种不同特性的液态金属膜流实验,并采用传统可视化方法获得了展向磁场存在时镓铟锡和锂在导电底板形成的液膜流动表面特征.实验结果表明:无磁场时,两种液态金属膜流流动表面波动特性与常规流体膜流均一致,即随着流动雷诺数的增加表面波动变得更为混乱;而展向磁场存在时,镓铟锡膜流表面波动变得更为规则,且沿着磁场方向平行排列,表现为拟二维波动的特征;而锂膜流却产生了明显的磁流体力学阻力效应,表现为在流动方向局部产生锂滞留现象,且滞留点随雷诺数增大向下游移动.最后通过膜流受力分析,进一步阐述了锂膜流受到比镓铟锡膜流更为严重磁流体力学效应影响的原因.     

聚变堆相关的液态金属膜流初步实验研究

在磁约束核聚变堆的面对等离子部件设计中,液态金属锂膜流因具有带走杂质、保护面对等离子固壁等优点而被认为是优选方案之一. 然而,如何克服聚变堆中强磁场环境下产生的磁流体力学效应并形成大面积均匀铺展锂膜流动是目前亟需解决的问题.本文通过搭建室温液 态镓铟锡回路和高温液态锂回路,开展了两种不同特性的液态金属膜流实验, 并采用传统可视化方法获得了展向磁场存在时镓铟锡和锂在导电底板形成的液膜流动表面特征.实验结果 表明: 无磁场时,两种液态金属膜流流动表面波动特性与常规流体膜流均一致, 即随着流动雷诺数的增加表面波动变得更为混乱; 而展向磁场存在时,镓铟锡膜流表面波动变得更为规则, 且沿着磁场方向平行排列,表现为拟二维波动的特征; 而锂膜流却产生了明显的磁流体 力学阻力效应,表现为在流动方向局部产生锂滞留现象, 且滞留点随雷诺数增大向下游移动. 最后通过膜流受力分析,进一步阐述了锂膜流受到比镓铟锡膜流更为严重磁流体力学效应影响的原因.      

介绍一种新的压电材料——铌酸锂晶体

铌酸锂晶体是一种新的人工晶体,多用于激光、无线电等方面。由于它有良好的压电性能,也可以用作压力敏感元件。其最大的特点是Z切割的晶片有较小的侧向灵敏度,因而可以和目前大量应用的天然晶体电气石(Z切割)比美。在电气石货源不畅的情况下,人造晶体铌酸锂确实是一种较好的压电材料。      

声表面波谐振器频率-温度行为分析

声表面波（SAW）器件以其优良的性能广泛应用于雷达、通讯和日常用品等领域。然而，随着器件工作频率的不断升高，温度对器件频率稳定性的影响也越来越严重。因此，研究声表面波器件的温度效应，并在变温情况下保持SAW器件的频率稳定性至关重要。本文采用增量型的拉格朗日方程分析受温度影响的声表面波频率漂移问题。用频率-温度系数（TCF）作为评价频率-温度行为的标准。设计了一个具有温度补偿层的双层SAW谐振器模型，降低了器件的频率-温度系数。通过尺寸优化，LiNbO3-AlN结构的SAW谐振器在25℃（参考温度）下的频率温度系数TCF接近0ppm/℃。SAW谐振器的波长为4μm，谐振频率为1214.9MHz。     

有限液体负载下压电平板声板波理论分析

主要推导平板声板波受有限液体负载后能量衰减与波速改变情形, 以部分波传理论分析该受液体负载的压电平板波传行为, 并以一128$^{\circ}Y$向切角的铌酸锂芯片为例,分析前20个声板波受水与甘油负载下 的能量衰减,并固定某一平板板波, 针对不同甘油厚度负载下, 计算其相速度与衰减变化,该理论分析对于液体负载下的平板板波传感器应用具有极大的参 考价值.     

陀螺效应对转子横向振动的影响分析

举例说明了在动力转子系统中陀螺效应对实际模型的影响。着重分析了转子陀螺效应对进动角速度、振型以及临界角速度的影响。并应用状态空间法求解陀螺系统的本征值问题。数值结果表明，在一些工程问题中，陀螺力对于转子系统振动特性的影响是不能忽略的。     

声表面波谐振器频率-温度行为分析

声表面波（SAW）器件以其优良的性能广泛应用于雷达、通讯和日常用品等领域。然而,随着器件工作频率的不断升高,温度对器件频率稳定性的影响也越来越严重。因此,研究声表面波器件的温度效应,并在变温情况下保持SAW器件的频率稳定性至关重要。本文采用增量型的拉格朗日方程分析受温度影响的声表面波频率漂移问题。用频率-温度系数（TCF）作为评价频率-温度行为的标准。设计了一个具有温度补偿层的双层SAW谐振器模型,降低了器件的频率-温度系数。通过尺寸优化,LiNbO3-AlN结构的SAW谐振器在25℃（参考温度）下的频率温度系数TCF接近0ppm/℃。SAW谐振器的波长为4μm,谐振频率为1214.9MHz。     

Surface acoustic wave MEMS gyroscope

The design and performance evaluation of a surface acoustic wave (SAW) MEMS gyroscope is presented in this paper. This gyroscope is an integration of a SAW resonator and a SAW sensor. The SAW resonator is used to setup a stable reference vibration and SAW sensor is used for the detection of the secondary SAW generated by the Coriolis force. Further to this resonator, strategically positioned metallic dots that form an array along the standing wave anti-node locations are subjected to the reference vibratory motion. These vibrating dot arrays through the Coriolis effect will generate secondary SAW, which is picked up by the SAW sensor. The SAW resonator is designed and optimized using coupling-of-modes (COM) theory. In view of its one-layer planar configuration, this gyroscope can be implemented easily for applications requiring conformal mounting onto a surface of interest. This SAW gyroscope can be competitively priced inherently rugged, reliable and very sensitive. It is also capable of being wirelessly interrogated, without any sensor power source.     

控制力矩陀螺用主动电磁轴承数字控制系统设计与实现

讨论了以TMS320VC33为核心的数字控制系统硬件结构。针对磁悬浮控制力矩陀螺转子的大惯量、小跨距、扁平转子和高速旋转时的陀螺效应，采用积分分离和不完全微分PID加交叉反馈控制策略。实验证明，该系统能够有效地抑制高速转子的陀螺效应，达到控制力矩陀螺电磁轴承高速稳定运行的要求。     

Nonlinear instabilities in a vibratory gyroscope subjected to angular speed fluctuations

Nonlinear instabilities in a single-axis vibrating MEMS gyroscope that is subjected to periodic fluctuations in input angular rates are investigated. For the purpose of characterizing the bifurcation behavior associated with the steady-state, when the angular rate input is subject to small intensity periodic fluctuations, dynamic behavior of periodically perturbed nonlinear gyroscopic systems is studied in detail. An asymptotic approach based on the method of averaging has been employed for this purpose, and closed-form conditions for the frequency response due to parametric resonances have been obtained. This behavior has been illustrated via amplitude-frequency plots.     

Green’s-function method for modeling surface acoustic wave dispersion in anisotropic material systems and determination of material parameters

A Green’s-function method for modeling propagation of surface acoustic waves in anisotropic nanolayered materials is reviewed. The mathematical model, developed at NIST, provides a computationally efficient inversion algorithm for determination of the material parameters of the film, such as its elastic constants and density, from observed dispersion of the surface acoustic waves. The application of the method to a 306 nm thick TiN film having transverse isotropy on a single crystal Si substrate is discussed as an example. The errors in the values of the parameters determined by using the inversion algorithm and the question of uniqueness of the values of the parameters are discussed in detail. It is suggested that, at least in the example considered in this paper, the SAW dispersion can be used to determine any two parameters of the film, provided other parameters are known by independent measurements. In particular, the values of c₁₁ and the density of the film, obtained from the measured SAW dispersion, are the most reliable and the value of c₄₄ is the least reliable. The method is extended to account for defective bonding between the film and the interface and the effect of an intermediate layer of silica between the film and the substrate.     

某型液浮陀螺浮子结构的热应力分析

本文以液浮陀螺的浮子结构有限元模型为基础,对某种浮子结构进行了热应力分析,得出在陀螺浮子处于工作温度场的情况下,该浮子结构中的最大热应力值,指出其所用材料的不合理处,为以后陀螺仪设计时材料的选取提供重要数据依据。     

Elastic fields in rotating transversely isotropic media

Representation of elastic fields in terms of scalar functions, which permit reducing the problems of determining these fields to determining scalar potentials, are generalized to the case of transversely isotropic media rotating at a constant angular velocity. Relations for calculating the parameters of surface acoustic waves (SAW) propagating in a rotating transversely isotropic halfspace with various directions of the medium material symmetry axis with respect to the half-space surface are given.     

Propagation characteristics of thermoelastic waves in piezoelectric (6 mm class) rotating plate

The propagation of Lamb waves in a homogeneous, transversely isotropic (6 mm class), piezothermoelastic plate rotating with uniform angular velocity about normal to its boundary has been investigated. The generalized (non-classical) theories of thermoelasticity in contrast to Sharma and Pal [Sharma, J.N., Pal, M., 2004. Lamb wave propagation in transversely isotropic piezothermoelastic plate. J. Sound Vib. 270, 587–610] have been used to investigate the problem. The surfaces of the plate are subjected to stress free, thermally insulated/isothermal and electrically shorted boundary conditions. Secular equations for wave propagation modes in the plate are derived from a coupled system of governing partial differential equations of linear piezothermoelasticity. After obtaining the complex characteristic roots with the help of Descartes' algorithm, the transcendental secular equations have been solved by functional iteration numerical technique to compute phase velocity and attenuation coefficient. Finally, in order to illustrate the analytical development, numerical solution of secular equations is carried out for PZT-5A piezo-thermoelastic material. The corresponding simulated results of various physical quantities such as phase velocity, attenuation coefficients, specific loss factor of energy dissipation, thermo-mechanical coupling factor and relative frequency shifts have been presented graphically for both rotating and non-rotating plates for comparison purpose. There is a scope for extension of the present work to other classes of piezo/pyroelectric crystals. The study will be useful in design and construction of gyroscope, rotation sensors, temperature sensors and other pyro/piezoelectric surface acoustic wave (SAW) devices.     

Modelling and analysis of a single gimbal gyroscopic energy harvester

This work investigates the non-linear dynamics of a single gimbal gyroscopic energy harvester, excited by a harmonic moment about 1 and 2 axes simultaneously. The governing equations of motion are derived and a numerical model is developed to analyse the forced system response in all three rotational degrees of freedom. Simulations showing the effect of the harmonic forcing frequency and the gyroscopic damping are presented. The results identify the characteristic motion responses and available power of a single gimbal gyroscopic energy harvester including the development of the non-linear responses.     

Propagation of acoustic surface waves on a phononic surface investigated by transient reflecting grating spectroscopy

We present a study of surface acoustic waves (SAW) propagation on a 1D phononic surface (PS) by mean of an heterodyne-detected transient reflecting grating experiment. We excited and detected coherent stationary SAWs characterized by variable wave-vectors. The measured SAW frequencies enables the characterization of the band diagram of this PS sample beyond the first Brillouin zone (BZ). Four different SAW frequencies have been revealed, whose band diagram show articulated dispersion phenomena. In order to address the nature of the investigated SAWs, the experimental results are compared with a numerical simulation of elastic modes based on a finite element model. The observed SAWs are addressed to four Bloch waves characterized by different frequencies and surface energy localization. Moreover, we measured the SAW propagation on a flat non-phononic part of the sample surface and compared it with results from the PS.