拉曼光反射镜隔振平台设计及性能测试

为提高原子干涉重力仪拉曼光相位稳定性,降低拉曼光反射镜振动噪声对原子干涉仪测量精度的影响,设计并研制了一种适用于小型化原子干涉重力仪拉曼光反射镜隔振平台。通过COMSOL Multiphysics有限元分析和激光干涉仪测试验证了其隔振性能。根据原子干涉重力仪对噪声控制的要求,对隔振平台在60～200 Hz内的减振效果进行仿真,将仿真结果作为试验的指导,用扫描式激光干涉仪配合标准振动台,对装载到隔振平台上的拉曼光反射镜的振动进行了测试,结果符合仿真结论。     

InGaAs红外探测器低频噪声研究

红外探测器的低频噪声是制约器件能否应用于空间遥感的关键因素之一.本文测试了典型的铟镓砷(InGaAs)红外探测器的低频噪声,测试结果表明器件的Hooge系数αH=2×10-5～7×10-5,噪声拐点较大.讨论了暗电流与器件低频噪声的关系,比较了不同钝化工艺研制的器件的低频噪声,结果表明通过加强表面钝化工艺可有效地降低器件的低频噪声.     

一种用于测量重力梯度的扭秤装置

基于扭秤测量重力梯度的原理,设计一款扭秤重力梯度仪,该仪器由扭秤系统、角度测量系统、振幅衰减系统、转台、真空容器5部分构成。针对扭秤悬挂系统稳定的时间过长,极大地影响了重力梯度的测量效率的问题,采用PID控制技术,设计了振幅衰减系统。仿真结果表明:曲率及水平重力梯度的测量精度可达0.5E(1E=1×10^-9m/s²),测量一组重力梯度的极限效率优于1h。     

颗粒阻尼吸振器用于轨道系统减振降噪效果研究

颗粒阻尼器（Particle damper）是一种简单而高效的减振控制装置，但其目前在轨道工程领域还处在应用起步阶段。为探讨颗粒阻尼器在整治地铁轨道振动噪音的可行性，设计并开发一种新型颗粒阻尼吸振器，在某地铁区间上线安装使用后验证其减振降噪效果。新型阻尼器具有结构简单、稳定性好、参数可调等结构特点，可适用于恶劣复杂的工作环境。锤击测试说明了该阻尼器具有高阻尼大阻抗的优点，对振动峰值具有突出的抑制效果。在线实测数据表明：新型阻尼器可在较宽频段内降低钢轨的垂向和横向振动，在200 Hz以上频段效果显著。安装阻尼器后车辆辐射噪声等效声级降低了3.5 dB(A)，在500 Hz主频处插入损失可达5.6 dB(A)。     

自适应系统在单频激光干涉仪上的应用研究

通过对单频激光干涉仪焦平面上等倾干涉条纹的能量分析和环境因素带来的随机噪声分析,研制一种自适应系统。该系统采用了四阶累积量计算法、信号滤波和信号直流分量提取算法。实验结果表明,可有效处理噪声信号,提取信号直流分量,从而提高直流分量跟踪精度。将该系统安装在单频激光干涉仪上,在非实验室环境条件下其线性测长准确度可达0.9×10^-6 L,测量重复性为0.09 μm。     

Ti−6Mo−5V−3Al−2Fe−2Zr合金热变形行为及热加工图

目的 建立近β钛合金Ti−6Mo−5V−3Al−2Fe−2Zr(质量分数)的热变形本构方程,绘制热加工图,确定该合金的流变失稳区和适宜加工区,为其在工业生产中热加工工艺参数的制定提供指导。方法 在变形温度700~ 850 ℃、应变速率0.000 5~0.5 s⁻¹、真应变0.7的条件下,对近β钛合金Ti−6Mo−5V−3Al−2Fe−2Zr进行热压缩实验;基于Arrhenius方程建立该合金的热变形本构方程,并对方程进行验证;根据Prasad失稳准则,构建该合金的热加工图。结果 该合金的流变应力随着变形温度的升高而减小,随着应变速率的增大而增大;其热变形激活能为226.29 kJ/mol,本构方程为;通过热变形本构方程得到的峰值应力计算值与实验值平均误差为4.21%。结论 建立的热变形本构方程预测了流变应力,描述了该合金的热变形行为;通过叠加合金的能量耗散图和流变失稳图,获得了该合金的热加工图。基于热加工图确定该合金的流变失稳区为变形温度700~755 ℃与784~850 ℃、应变速率0.5~0.05 s⁻¹,最佳加工区为变形温度836~850 ℃、应变速率0.000 5~0.005 s⁻¹。     

15MHz分子污染监测仪的研制

石英晶体微量天平测试技术可用于监测非金属材料出气和航天器敏感系统表面的分子污染沉积。在地面分子污染监测设备研制的基础上,针对空间应用,设计研制了15MHz温控分子污染监测仪。它具有质量轻、体积小、功耗低的特点。通过一系列测试和地面试验,表明它的监测灵敏度可达2.94×10-9g1cm2,在-40～30℃范围内对探头的控温精度优于0.18℃,并可通过计算机控制其工作温度点,实时数据采集系统具有1次1s的采集、处理功能和良好的软件操作界面。     

一种计算航船对近海海洋环境噪声贡献的算法

为了研究浅海中低频段的海洋环境噪声，文章构建了一种计算航船对近海海洋环境噪声贡献的算法，利用某海域航船信息，结合实际水文参数，对该海域的航运噪声进行了仿真计算。航船信息通过访问船舶自动识别系统数据库获取。主要关注50~400 Hz的中低频段，将仿真计算结果和实验数据进行对比，验证了算法的可靠性，并进行了误差分析。利用该算法可获取接收点处航船噪声的水平方向分布特点，并可初步定量分析航船噪声对海洋环境噪声的贡献。     

基于激光干涉仪同步测量的动态校准装置

为满足时变几何量的瞬时动态测试需求,研制了一种基于激光干涉仪同步测量的动态校准装置。该装置采用直线运动导轨和运动发生器、长度标准器激光干涉仪,以基于GNSS驯服时钟的同步触发器实现同步测量并确保时间准确稳定,并使用动态校准软件实现控制一体化。经综合分析激光干涉仪的最大允许误差、直线运动导轨的直线度、环境因素、触发信号间时延及激光干涉仪测量时延等因素,该装置的长度示值的测量不确定度为Q[1.8μm, 3×10^-7L](k=2)。与同型号激光干涉仪的比对实验和激光跟踪仪瞬时长度测试实验,证明了不确定度评定的合理性以及该装置在瞬时动态准确度测试中的可行性。     

用于引力波探测的星间激光干涉测量模拟系统

星间激光干涉仪具有比地面干涉仪更长的干涉臂(10⁶ km),能够探测更低频段0.1 mHz～1 Hz的引力波。星间激光干涉仪具有典型的应答式外差干涉仪结构,其本质是一个光学锁相环。在地面环境下搭建模拟的星间激光干涉仪,成功将从激光器的频率锁定到稳频的主激光器频率上。结果显示：锁相环的锁定时间超过2×10⁴ s,满足了低频信号的探测条件;在较短位移和较长位移的不同条件下,干涉仪无粗大误差。经过分析得出：温度、气压等环境扰动带来的噪声是制约干涉仪精度的关键因素。     

GRAIL: A 10 mk, 100 ton spherical gravitational wave antenna

Massive metallic spheres cooled to millikelvin temperatures could reach quantum-limited sensitivities high enough to detect gravitational waves from supernovae explosions up to 100–200 Mpc which would include millions of galaxies. They could provide sensitivity (in the frequency range above 700 Hz) and directionality, superior to the large interferometer arrays presently under construction, which will be better at lower frequencies and can have a larger bandwidth. World wide gravitational wave observatories will probably use both types of detectors. In this paper we give a brief overview of the problems involved in making a resonant spherical gravitational wave detector of very large mass working in the low millikelvin range.     

Modeling the Dynamics of a Gravitational Interferometer in the Field of the Earth

The results are given of a numerical modeling of the behavior of a Fabry–Perot–Michelson optical interferometer utilizing suspended mirrors in the variable gravitational field of the Earth. The possibility is demonstrated of separating and reconstructing the signals in the interferometer arms and of filtering the coherent noise. A prediction is made of the maximum attainable sensitivity of the apparatus to variations of the gravitational gradient.     

A Six-DOF Buoyancy Tank Microgravity Test Bed with Active Drag Compensation

Ground experiment under microgravity is very essential because it can verify the space enabling technologies before applied in space missions. In this paper, a novel ground experiment system that can provide long duration, large scale and high microgravity level for the six degree of freedom (DOF) spacecraft trajectory tracking is presented. In which, the most gravity of the test body is balanced by the buoyancy, and the small residual gravity is offset by the electromagnetic force. Because the electromagnetic force on the test body can be adjusted in the electromagnetic system, it can significantly simplify the balancing process using the proposed microgravity test bed compared to the neutral buoyance system. Besides, a novel compensation control system based on the active disturbance rejection control (ADRC) method is developed to estimate and compensate the water resistance online, in order to improve the fidelity of the ground experiment. A six-DOF trajectory tracking in the microgravity system is applied to testify the efficiency of the proposed compensation controller, and the experimental simulation results are compared to that obtained using the classic proportional-integral-derivative (PID) method. The simulation results demonstrated that, for the six-DOF motion ground experiment, the microgravity level can reach to 5 × 10^?4 g. And, because the water resistance has been estimated and compensated, the performance of the presented controller is much better than the PID controller. The presented ground microgravity system can be applied in on-orbit service and other related technologies in future.     

Torsion dynamometers

Conclusions Pendulum dynamometers are preferably used in the best machines for testing materials with static loads.The existing designs of torsion dynamometers have as yet no substantial advantages as compared with those of the pendulum type.Further attempts in producing low-inertia torsion dynamometers for static machines should aim at providing torsion bars with large twist angles,of the order of 0.5–0.7 rad.Torsion dynamometers in combination with inertialess indicators are preferable to those of the pendulum type for use in machines intended for high-speed loading and deformations.     

Cryogenically cooled ultra low vibration silicon mirrors for gravitational wave observatories

Interferometric gravitational wave observatories recently launched a new field of gravitational wave astronomy with the first detections of gravitational waves in 2015. The number and quality of these detections is limited in part by thermally induced vibrations in the mirrors, which show up as noise in these interferometers. One way to reduce this thermally induced noise is to use low temperature mirrors made of high purity single-crystalline silicon. However, these low temperatures must be achieved without increasing the mechanical vibration of the mirror surface or the vibration of any surface within close proximity to the mirrors. The vibration of either surface can impose a noise inducing phase shift on the light within the interferometer or physically push the mirror through oscillating radiation pressure. This paper proposes a system for the Laser Interferometric Gravitational-wave Observatory (LIGO) to achieve the dual goals of low temperature and low vibration to reduce the thermally induced noise in silicon mirrors. Experimental results are obtained at Stanford University to prove that these dual goals can be realized simultaneously.     

Bi/3DPG composite structure optimization realizes high specific capacity and rapid sodium-ion storage

As an anode material for sodium-ion batteries (SIBs), bismuth (Bi) has attracted widespread attention due to its suitable voltage platform and high volumetric energy density. However, the severe volume expansion of Bi during charging and discharging leads to a rapid decline in battery capacity. Loading Bi on the graphene can relieve volume expansion and improve electrochemical performance. However, excessive loading of Bi on graphene will cause the porosity of the composite material to decrease, which leads to a decrease of the Na⁺ transmission rate. Herein, the Bi/three-dimensional porous graphene (Bi/3DPG) composite material was prepared and the pore structure was optimized to obtain the medium-load Bi/3DPG (Bi/3DPG-M) with better electrochemical performance. Bi/3DPG-M exhibited a fast kinetic process while maintaining a high specific capacity. The specific capacity still remained at 270 mA·h·g⁻¹ (93.3%) after 500 cycles at a current density of 0.1 A·g⁻¹. Even at 5 A·g⁻¹, the specific capacity of Bi/3DPG-M could still reach 266.1 mA·h·g⁻¹. This work can provide a reference for research on the use of alloy–graphene composite in the anode of SIBs.     

Analysis of light noise sources in a recycled Michelson interferometer with Fabry-Perot arms

We present a method by which the effect of laser field variations on the signal output of an interferometric gravitational wave detector is rigorously determined. Using the Laser Interferometer Gravitational Wave Observatory (LIGO) optical configuration of a power recycled Michelson interferometer with Fabry-Perot arm cavities as an example, we calculate the excess noise after the input filter cavity (mode cleaner) and the dependence of the detector strain sensitivity on laser frequency and amplitude noise, radio frequency oscillator noise, and scattered-light phase noise. We find that noise on the radio frequency sidebands generally limits the detector's sensitivity.     

非晶态PdCuSi的内耗和DSC研究

用葛摆测量了ａ－ＰｄＣｕＳｉ合金的内耗－温度曲线，证明在该合金的Ｔｇ和Ｔｘ温度附近有两个内耗峰Ｐ１和Ｐ２．Ｐ２峰是与非晶晶化有关的内耗峰，而Ｐ１峰可能是弛豫型的内耗峰．分析了倒扭摆和Ｃｏｌｌｅｔｔｅ摆的灵敏度，阐述了这两种摆不适用于测量ａ—ＰｄＣｕＳｉ类合金的内耗峰．     

High performance testbed for four-beam infrared interferometric nulling and exoplanet detection

Technology development for a space-based infrared nulling interferometer capable of earthlike exoplanet detection and characterization started in earnest in the last 10 years. At the Jet Propulsion Laboratory, the planet detection testbed was developed to demonstrate the principal components of the beam combiner train for a high performance four-beam nulling interferometer. Early in the development of the testbed, the importance of "instability noise" for nulling interferometer sensitivity was recognized, and the four-beam testbed would produce this noise, allowing investigation of methods for mitigating this noise source. The testbed contains the required features of a four-beam combiner for a space interferometer and performs at a level matching that needed for the space mission. This paper describes in detail the design, functions, and controls of the testbed.