一种有效的加速度计静态模型辨识方法

研究了惯性元器件加速度计静态模型参数的标定问题，首先给出了加速度计静态数学模型，并在此基础上研究了一种有效的加速度计标度因数，安装误差的标定方法，给出了具体的实验方法和数据处理方法，理论分析和实验试验表明所述方法能够有效地标定加速度计静态模型各项参数。     

三维等灵敏度低耦合弹性机构的设计和优化

振动对仪器和机床的精度都有较大影响,对其进行准确检测和分析,是实现振动有效控制的前提。 本研究提出了一种 高灵敏度和低耦合三维弹性机构及其参数优化方法。 介绍了三维弹性机构的构型,并通过理论建模、参数优化和仿真分析完成 了三维弹性机构的设计和优化,最后将该弹性机构与高灵敏度、低耦合传感系统相结合,研制了高性能三维低频加速度计系统, 并实测了加速度计系统的性能参数。 根据实验结果,使用该弹性机构的三维加速度计的灵敏度优于 2. 0 V/ (m·s -2 ),耦合误差 低于 1. 5% ,以及频率响应范围为 1~ 13 Hz,符合设计要求。 因此,本研究所提出的三维弹性机构具有三维等灵敏度和低耦合的 特点,可以广泛应用于各种三维加速度计。     

梳齿结构与振动梁复合的硅微谐振式加速度计非线性振动特性

硅微谐振式加速度计的非线性振动可以导致振动幅度噪声耦合到频率输出进而恶化器件的噪声性能,因此有必要对谐振式加速度计的非线性振动特性进行评估及优化,拓展线性振动范围。本文针对所设计的基于梳齿结构与振动梁复合的硅微谐振式加速度计进行了仿真与实验分析。首先对加速度计结构使用COMSOL仿真软件进行了非线性仿真分析,该方法通过在谐振梁的振动方向上施加一个静力,得到力与位移之间的关系,计算出非线性三次项系数k3,eff和线性系数keff的比值约为2.13×10^10 m^-2。然后,对双端固支音叉(DETF)进行扫频测试,得出DETF的非线性振动频响曲线。根据Duffing方程对实验数据进行拟合,得出器件两个DETF的非线性三次项系数k3,eff和线性系数keff的比值分别为2.24×10^10 m^-2和2.19×10^10 m^-2。仿真值与测试值的误差分别为5.2%和2.8%。实验结果与仿真值吻合得较好,印证了仿真方法的有效性和测试数据的可靠性。最后,对所设计的谐振加速度计进行非线性分析,当振幅小于35.4 nm时,DETF工作在线性区,可为后续谐振式加计的控制电路设计提供参考。     

井斜动态测量离心力的修正

介绍了井斜的危害,研制了一种新的井斜动态测量试验台,分析了底部钻具的强烈振动和随机转动对井斜测量的影响,转动引起的离心力会使加速度传感器测试信号失真,则用两个加速度传感器对离心力的影响进行修正,为井斜精确测量奠定基础。     

加速度计的频率特性研究

建立了一般加速度计摆组件的数学模型,分析了其工作原理,对该加速度计在不同工作状态下的频率特性进行了理论推导、分析研究和具体测试。该研究可为产品试验、使用和改进提供参考依据。     

综合液冷盲插系统设计及验证

文中介绍了某综合液冷盲插系统的结构设计方案以及电液一体化盲插设计,同程管网设计,轻量化、模块化设计等关键技术。为了满足恶劣机载条件下的散热性能和力学性能,对该系统的流量分配和振动冲击性能进行了仿真分析和计算。最后对综合液冷系统进行了流阻测试和振动测试,验证了仿真分析的合理性和产品的可靠性。文中的设计思路和方法可供同类产品设计参考和借鉴。     

机载小功率热电制冷系统性能分析

以机载热电制冷模块为研究平台,在已设定飞机参数的条件下,以工作电流为变量,得出了此系统在三种不同飞行高度下工作时的制冷量、制冷系数的变化曲线,利用熵产最小法进行了系统性能的评估,并计算了系统的代偿损失。所作工作为开展机载小功率热电制冷系统研究提供了初步理论指导,具有一定的参考意义。     

微加速度计在冲击载荷作用下的失效分析

抗冲击性是加速度计的一个主要性能指标,跌落实验则是一种测试结构冲击作用的有效方式,本文利用跌落实验种折叠梁式微加速度计在冲击载荷作用下的失效模式进行了研究。实验发现在微加速度计中主要存在两种主要的失效模式,即微梁结构的整体破坏和微结构在横向之间的粘附。应用拟静态和能量方法给出微结构在中冲击载荷下的响应。     

Multi-rate Kalman filtering for the data fusion of displacement and acceleration response measurements in dynamic system monitoring

Many damage detection and system identification approaches benefit from the availability of both acceleration and displacement measurements. This is particularly true in the case of suspected non-linear behavior and permanent deformations. In civil and mechanical structural modeling accelerometers are most often used, however displacement sensors, such as non-contact optical techniques as well as GPS-based methods for civil structures are becoming more common. It is suggested, where possible, to exploit the inherent redundancy in the sensor information and combine the collocated acceleration and displacement measurements in a manner which yields highly accurate motion data. This circumvents problematic integration of accelerometer data that causes low-frequency noise amplification, and potentially more problematic differentiation of displacement measurements which amplify high-frequency noise. Another common feature of displacement-based sensing is that the high-frequency resolution is limited, and often relatively low sampling rates are used. In contrast, accelerometers are often more accurate for higher frequencies and higher sampling rates are often available. The fusion of these two data types must, therefore, combine data sampled at different frequencies. A multi-rate Kalman filtering approach is proposed to solve this problem. In addition, a smoothing step is introduced to obtain improved accuracy in the displacement estimate when it is sampled at lower rates than the corresponding acceleration measurement. Through trials with simulated data the procedure's effectiveness is shown to be quite robust at a variety of noise levels and relative sample rates for this practical problem.     

Straightness and flatness evaluation using data envelopment analysis

In today's world of precision engineering, robustness and accuracy in the evaluation of the form tolerances are considered as competitive advantages for manufacturing enterprises. Amongst various methods for accurate and robust evaluation, which have been studied, nonlinear optimization methods based on operational research have proved to be successful as far as they can ensure unique and global convergence in practical applications. However, it is well known that ensuring the convergence is the most difficult thing to deal with for a nonlinear optimization technique because the performance is in general highly sensitive to parameter setting. Therefore, this paper introduces a robust linear programming formulation-based algorithm in which the performance is not dependent on the quality of parameters. Interestingly, in this algorithm, the data envelopment analysis technique is used to form a convex hull that decides the minimum enclosed zone in a robust manner. From the computational experiments, it is shown that the proposed algorithm can be a promising alternative to the traditional nonlinear optimization method for straightness and flatness evaluation.     

虚拟仪器在空压机性能测试系统中的应用

美国NI公司的虚拟仪器软件LabVIEW是目前应用最广、发展最快、功能最强的图形化软件开发集成环境。设计了应用虚拟仪器软件LabVIEW及其它硬件产品来组建压缩机性能测试系统的方案,分析了该系统的主要功能及特点,该系统比传统测试方法更为简便、准确和稳定。     

跨音速轴流压缩机性能预测逐排模型研究

使用准一维逐排模型预测两台跨音速轴流压缩机的总性能,并与试验数据对比.结果表明:使用选定的参考攻角、损失和落后角模型的逐排模型,能够有效地预测轴流压缩机的总性能,计算结果与试验数据吻合较好.     

一种高精度石英挠性加速度计自动测试系统设计

石英挠性加速度计(简称石英加表)作为惯性平台的核心器件,其精度、可靠性是国内外研究的重点。该文研发了一套加速度计自动测试系统,采用强制均温和半导体制冷片调温的温控仪实现了采样电阻的精确温控,可针对不同采样电阻对测试精度的影响,应用采样电阻补偿算法,有效提高了温度稳定性和采样测量精度。经试验验证,采样电阻最小误差为百万分之4.3,可控采样电阻温度变化小于0.02℃,输出最大温度漂移为0.01 V,满足实际工程需求。     

A machine learning approach for the condition monitoring of rotating machinery

Rotating machinery breakdowns are most commonly caused by failures in bearing subsystems. Consequently, condition monitoring of such subsystems could increase reliability of machines that are carrying out field operations. Recently, research has focused on the implementation of vibration signals analysis for health status diagnosis in bearings systems considering the use of acceleration measurements. Informative features sensitive to specific bearing faults and fault locations were constructed by using advanced signal processing techniques which enable the accurate discrimination of faults based on their location. In this paper, the architecture of a diagnostic system for extended faults in bearings based on neural networks is presented. The multilayer perceptron (MLP) with Bayesian automatic relevance determination has been applied in the classification of accelerometer data. New features like the line integral and feature based sensor fusion are introduced which enhance the fault identification performance. Vibration feature selection based on Bayesian automatic relevance determination is introduced for finding better feature combinations.     

Uniaxial fiber Bragg grating accelerometer system with temperature and cross axis insensitivity

In this paper we describe the implementation and test of an optical fiber based accelerometer with cross axis insensitivity. The accelerometer uses two matching fiber Bragg gratings which are also responsible by the demodulation of the wavelength encoded information. The accelerometer was tested in a reinforced concrete slab, of a 3-storey building located at the University of Aveiro, Portugal. A maximum error of 0.25% for the slab eigenfrequencies was obtained when compared with the values acquired by an electronic sensor.     

An advanced nonlinear model of a low-g MEMS accelerometer for a computer pen

This paper presents an improvement in the gesture reconstruction for a computer pen using the inertial principle. The computer pen is equipped with a complete, miniaturized, six-degrees-of-freedom, inertial measurement unit in order to reduce the error of the pen’s orientation during the gesture stroke and to reduce the error of the calculated pen tip’s position on the piece of paper. The performance of the computer pen is improved by calibrating the MEMS accelerometer. The presented research focuses on the advanced modeling of the nonlinear voltage output of a triple-axis low-g MEMS accelerometer. The model considers the interacting influence of the low-g accelerations between the sensing axes in an arbitrarily oriented pen without any required knowledge about the underlying performance of the MEMS accelerometer. In combination with the attitude-compensation and zero-velocity-compensation techniques the positional accuracy of the pen’s tip on the paper is greatly improved.     

Pipeline for illumination correction of images for high‐throughput microscopy

The presence of systematic noise in images in high‐throughput microscopy experiments can significantly impact the accuracy of downstream results. Among the most common sources of systematic noise is non‐homogeneous illumination across the image field. This often adds an unacceptable level of noise, obscures true quantitative differences and precludes biological experiments that rely on accurate fluorescence intensity measurements. In this paper, we seek to quantify the improvement in the quality of high‐content screen readouts due to software‐based illumination correction. We present a straightforward illumination correction pipeline that has been used by our group across many experiments. We test the pipeline on real‐world high‐throughput image sets and evaluate the performance of the pipeline at two levels: (a) Z′‐factor to evaluate the effect of the image correction on a univariate readout, representative of a typical high‐content screen, and (b) classification accuracy on phenotypic signatures derived from the images, representative of an experiment involving more complex data mining. We find that applying the proposed post‐hoc correction method improves performance in both experiments, even when illumination correction has already been applied using software associated with the instrument. To facilitate the ready application and future development of illumination correction methods, we have made our complete test data sets as well as open‐source image analysis pipelines publicly available. This software‐based solution has the potential to improve outcomes for a wide‐variety of image‐based HTS experiments.     

汽车起重机单缸插销机构性能试验台的研究

单缸插销机构作为当前汽车起重机的核心技术,代表了起重机伸缩臂技术的发展方向,其性能及其可靠性的提升是汽车起重机向更大吨位挑战的有力支撑。该文将提供一种其性能试验的研究思路,并给出了系统原理框图,可作为后续研究的参考依据。     

基于Windows的通风机性能试验数据处理系统

根据GB/T1236-2000标准的要求,开发研制了一种基于Windows窗口的通风机性能试验计算机辅助数据处理系统,详细介绍了处理系统软件采用的设计思想,界面与程序编写过程.实例应用证明,所开发的这一风机性能辅助数据处理系统,与传统的测试方法比较,具有方便、迅捷和计算准确的特点.     

Extracting reference voltages from measurement voltages for oil-water two-phase flow measurement of electrical impedance tomography

To apply electrical impedance tomography (EIT) for heterogeneous two-phase flow measurement, reference voltages have to be measured, which requires the entire pipeline filled with a homogeneous medium. Such process is often time-consuming, costly and infeasible in some cases. Reference voltages acquired initially could not be used later, because of electrical conductivity change of two-phase flow caused by temperature change or chemical reaction. It will be ideal if reference voltages could be extracted from measurement voltages. In this paper, a novel multiple measurements (MMs) method is proposed by data fitting and empirical formula to establish the mapping model from measurement voltages to reference voltages, and the effectiveness of the method is proved by the oil-water two-phase flow experiment. Compared with the measurement-scale feature (MSF) and best homogeneous (BH) methods, the proposed MMs method achieves 6.38% average relative error (RE) and 4.96% average volume fraction relative error (VFRE) in the test set. The work enables the accurate estimation of the reference voltage and thus the accurate measurement of the volume fraction of oil-water two-phase flows, which will broaden the application of EIT in the field of two-phase flow measurement.