单颗粒气溶胶实时在线监测飞行时间质谱仪的研制

介绍国内第一台采用空气动力学透镜进样系统的质谱仪。这种系统有效地提高进样效率和检测效率。本仪器优化双光束测径装置和激光解析电离装置的空间结构,缩短气溶胶漂移空间从而提高小颗粒的检测极限。     

Modified relative arrival time technique for sizing inclined cracks

In this paper, a modified relative time technique is proposed for estimating the length and the orientation of inclined cracks using ultrasonic B-scan signals. The proposed technique utilizes the relative position of the tip diffraction echo to the corner reflection echo in an ultrasonic B-scan image to estimate the crack length and the crack inclination angle. Both finite element simulated signals and experimental signals, which are obtained from a specimen with a 3 mm crack with different inclination angles, are used to evaluate the estimation error of the proposed technique. The results show that the proposed technique overcomes the shortcoming of the conventional relative arrival time technique in sizing inclined cracks.     

Ultrasonic bone localization algorithm based on time-series cumulative kurtosis

The design and optimization of protective equipment and devices such as exoskeletons and prosthetics have the potential to be enhanced by the ability of accurately measure the positions of the bones during movement. Existing technologies allow a quite precise measurement of motion—mainly by using coordinate video-cameras and skin-mounted markers—but fail in directly measuring the bone position. Alternative approaches, as fluoroscopy, are too invasive and not usable during extended lapses of time, either for cost or radiation exposure. An approach to solve the problem is to combine the skin-glued markers with ultrasound technology in order to obtain the bone position by measuring at the same time the marker coordinates in 3D space and the depth of the echo from the bone. Given the complex structure of the bones and the tissues, the echoes from the ultrasound transducer show a quite complex structure as well. To reach a good accuracy in determining the depth of the bones, it is of paramount importance the ability to measure the time-of-flight (TOF) of the pulse with a high level of confidence. In this paper, the performance of several methods for determining the TOF of the ultrasound pulse has been evaluated when they are applied to the problem of measuring the bone depth. Experiments have been made using both simple setups used for calibration purposes and in real human tissues to test the performance of the algorithms. The results show that the method used to process the data to evaluate the time-of-flight of the echo signal can significantly affect the value of the depth measurement, especially in the cases when the verticality of the sensor with respect to the surface causing the main echo cannot be guaranteed. Finally, after testing several methods and processing algorithms for both accuracy and repeatability, the proposed cumulative kurtosis algorithm was found to be the most appropriate in the case of measuring bone depths in vivo with ultrasound sensors at frequencies around 5 MHz.     

同轴线式相位法测量油井含水率

本文利用同轴传输线作传感器，测量油水混合水质的相位系数，研制了同轴线式相位法找水仪，从而得到油水混合介质的持水率。该仪器还实现了油井持水率以往难达到的连续测量，室内模拟井试验和初步现场试验看出本文提出的含水率测量新方法颇有前途。     

High-accuracy ultrasonic temperature measurement based on MLS-modulated continuous wave

Ultrasonic temperature measurement has the potential to improve measurement accuracy by increasing the length of a received signal due to its excellent performance with noise resistance. However, when the distance between the transmitter and receiver is limited, the received signal can be polluted by strong multiple echoes, which can significantly degrade temperature accuracy. This paper proposes a method for high-resolution ultrasonic temperature measurement. With the use of a maximum length sequence (MLS)-modulated continuous wave, the obstructive effect of echoes is effectively suppressed. A hybrid method is employed for accurate time-of-flight (TOF) estimation by incorporating both cross-correlation and phase shift (PS), which is the basis of highly accurate temperature measurement. The experimental results in distilled water show that the proposed method estimates TOF with a standard deviation of less than 0.3 ns, and temperature errors consistently remain within ±0.04 °C.     

超声波式数字测距仪的研究

介绍了超声波式数字测距仪的原理，主要论述了在测量中存在超声波的传播速度随着温度的变化和其它干扰信号对测量的影响问题，对这些存在的问题提出了解决的方法。     

An Accurate Ultrasonic Distance Measurement System with Self Temperature Compensation

Abstract

This study proposes an accurate distance measurement system which has self-temperature-compensation (STC) with the environmental average temperature in space, rather than a single point temperature. This system combines both the amplitude modulation (AM) and the phase modulation (PM) of the pulse-echo technique. The proposed system can reduce error caused by inertial delay and the amplitude attenuation effect when using the AM and PM envelope square waveform (APESW). The proposed system adopts two identical measurement hardware sets using the APESW ultrasonic driving waveform. The first set measures the sound velocity (the environmental average temperature information is also involved) as the result of the temperature compensation data for the second distance measuring set. Without using a temperature sensor, experimental results indicate that the proposed STC distance measurement system can accurately measure the distance. The experimental standard deviation of the linearity with respect to the distance is found to be 0.21 mm at a range of 50 to 500 mm. Moreover, the proposed system's temperature uncertainty effect produced a standard deviation of 0.093 mm, while the temperature sensor system's uncertainty effect produced a standard deviation of 0.68 mm. The STC manner is simple and can be easily adapted for robotic applications for which the temperature sensors can not easily be set up and placed. The main advantages of this STC distance measurement system are: high resolution, low cost, and ease of implementation.     

脉冲涡流无损检测技术应用研究

脉冲涡流与传统涡流不同，脉冲涡流通过测量磁场最大值出现的时间来确定缺陷的位置。对脉冲涡流的检测原理进行了分析，设计了脉冲波形发生器和垂直磁场检测电路，并通过试验对此方法进行了验证。     

Subsample interpolation bias error in time of flight estimation by direct correlation in digital domain

This work presents an investigation of the bias error introduced in time of flight estimation realized by subsample interpolation in digital domain. The time of flight estimation is accomplished based on the evaluation of the peak position of the cross correlation function. In order to cope with the discrete nature of the cross-correlation function, subsample estimation exploits three time domain interpolation techniques: parabolic, cosine, Gaussian and frequency domain interpolation using phase angle. An empirical equation relating the maximum value of the bias error to sampling frequency and signal parameters (center frequency and envelope bandwidth) has been derived. It is found that the maximum value of the bias error is in inverse cubic relation to sampling frequency and in quadratic relation envelope bandwidth for cosine interpolation. The maximum value of the bias error is in inverse cubic relation to sampling frequency and in quadratic relation to center frequency and envelope bandwidth for parabolic interpolation. The coefficients related to the approximation technique are given. Results can be applied for bias errors estimation or correction when fast subsample interpolation is used and application of phase domain interpolation is unacceptable due to processing speed limitations. The equations for minimum required sampling frequency are derived by balancing the interpolation error against Cramer–Rao lower bound.     

飞行试验中的发动机叶尖间隙测量方法

对飞行试验中的航空发动机叶尖间隙测量方法进行探讨,分析了实际飞行中影响发动机叶尖间隙的因素,在此基础上对叶尖间隙测量的试飞方法进行了探讨。     

切割钢丝波高波长自动测量系统

为了实现对切割钢丝波形与参数的自动化测量,本文研发了一种基于图像处理的切割钢丝自动测量系统。该系统使用图像测量法对钢丝的单幅图像进行采集、识别与处理,得出单幅图像中的波高波长参数。然后旋转钢丝,在钢丝旋转一周的过程中采集多幅图像,还原钢丝的3D结构模型,分离出钢丝的大小波,得出钢丝的真实参数。最后采用亚像素细分来提高图像测量的分辨率和重复精度。实验结果表明,该系统的分辨率可达0.1μm,大波波高测量精度小于±1μm,小波波高测量精度小于±3μm,不仅满足全自动、高重复精度的需求,在大小波识别分离方面也有着很高的准确率。

     

Volume estimation of merchandise using multiple range cameras

The ability of fast and automatic volume measurement of merchandise is of paramount importance in logistics. In this paper, we address the problem of volume estimation of goods stacked on pallets and transported in pallet trucks. Practical requirements of this industrial application are that the load of the moving pallet truck has to be measured in real-time, and that the measurement system should be non-invasive and non-contact, as well as robust and accurate. The main contribution of this paper is the design of simple, flexible, fast and robust algorithms for volume estimation. A significant feature of these algorithms is that they can be used in industrial environments and that they perform properly even when they use the information provided by different range devices working simultaneously. In addition, we propose a novel perception system for volume measurement consisting of a heterogeneous set of range sensors based on different technologies, such as time of flight and structured light, working simultaneously. Another key point of our proposal is the investigation of the performance of these sensors in terms of precision and accuracy under a diverse set of conditions. We also analyse their interferences and performance when they operate at the same time. Then, the analysis of this study is used to determine the final configuration of the cameras for the perception system. Real experiments proof the performance and reliability of the approach and demonstrate its validity for the industrial application considered.     

几种新型号二次离子质谱仪采用的新技术

本文简要叙述法国CAMECA公司 ,德国IONTOFGmbH公司新型的NanoSIMS5 0IMSWFIMSSCUITRATOFSIMSIV型二次离子质谱的特色 ,着重介绍这些仪器改进过的和新增加的仪器部件的原理、性能及功用     

转镜式高速摄影机角跟踪精度的检测

为了提高转镜式高速摄影机测量弹丸运动轨迹的精度,本文通过合理假设和理论推导,依据弹丸外弹道飞行运动模型得到了弹丸飞行过程的数学模型。结合室内检测条件,设计了用于转镜式高速摄影机角跟踪精度的检测装置并分析了测试原理。用该设备实测了转镜式高速摄影机的角跟踪精度,并对检测装置的测量不确定度来源进行了分析。结果显示:被测转镜式高速摄影机的角跟踪精度为(0.34±0.06)°,检测装置的相对不确定度为3.0\";不确定度来源主要为角度测量不确定度和焦距测量不确定度。实验结果表明,设计的检测装置具有较高的准确度和可靠性。     

Continuous analysis of move suppressed and shifted DMC

"Shifted DMC" (shifted dynamic matrix control) has been empirically shown to have significant improved closed-loop control characteristics over "move-suppressed DMC" where, in the latter, diagonal terms of the dynamic matrix DMC prediction model are augmented to reduce numerical ill conditioning. An added benefit of shifted DMC was that the so-called "shifting parameter," replacing the move suppression parameter, was easily found from the open-loop response. Therefore a novel analytical method, based on a closed form, continuous approximation to closed-loop DMC control, is introduced here and used to quantify the previous empirical results. The dependence of slow and fast time scales of the closed-loop response on the parameters is examined for move-suppressed and shifted DMC methods. It is found that in move-suppressed DMC the slow control time scale is sharply dependent upon the sampling time and move-suppression parameter and that these difficulties are eliminated in shifted DMC.     

电流平衡式无源积分型时分割乘法器功率测量误差分析

本文以电流平衡式时分割乘法器为研究对象,通过建立其数学模型给出了功率测量误差的表达式,利用计算机仿真对其动态误差进行全面分析.文中给出各类参数变化影响的测量误差曲线图,总结出几点在工程实践上有用的结论.     

基于TDC的L_(CR)波切向应力检测方法的研究

基于固体中声速与应力的关系以及临界折射纵波(critically refracted longitudinal wave,LCR)的产生机理,提出一种利用LCR波从表面检测物体内部切向应力的实施方法,并对测量系统的硬件结构和工作原理进行详细阐述。针对应力改变导致的LCR波传播时间的微量变化,系统采用基于逻辑门绝对传输时间原理工作的"时间—数字转换器"(time to digi-tal converter,TDC)来满足高精度的时间间隔测量要求。在测量过程中采用"单端发射—双端接收"的布局模式进一步降低测量误差,以提高应力检测的精度。     

Using ultrasonic pulse-echo B-scan signals for estimation of time of flight

Time of flight based methods are extensively used for detecting, locating and sizing faults in ultrasonic non-destructive testing and evaluation. In this paper, we investigate model-based estimation of the ultrasonic time of flight using B-scan signals. The Cramer–Rao bounds on the time of flight estimator for B-scan signals are derived and then compared to the Cramer–Rao bounds on the time of flight estimator for A-scan signals. Through this theoretical analysis, we show that the estimation based on B-scan signals significantly reduces the Cramer–Rao bound on the time of flight estimator. In addition, the resulting theoretical equation allows evaluating the improvement in the accuracy of estimating the time of flight. The theoretical lower bound is then compared to the variance of a maximum likelihood estimator which is obtained using a Monte Carlo simulation. The results show that the maximum likelihood estimator can achieve the lower bound on the variance of the time of flight estimator and hence it is an efficient estimator. This numerical result will complement the theoretical analysis by showing that the Cramer–Rao bound can be reached if a proper estimator is selected.     

高分辨电喷雾离子源三级四极杆-飞行时间质谱仪的研制

报道了实验室研制的电喷雾离子源 ,具有射频四极杆接口的高分辨飞行时间质谱 (ESI- QQQ- TOFMS)仪器。该仪器具有以下特点 :在离子调制区使用三组四极杆 ,有效地减少离子束的空间分散和能量分散 ;采用正负双脉冲推斥和离子垂直引入方式 ;经过优化设计的二级有网反射器 ;新颖的 MCP安装方法。经初步调试 ,该仪器的分辨本领已优于 1 0 ,0 0 0 ,质量测定精度优于 1 0× 1 0 - 6 。该仪器于 2 0 0 2年 6月通过了国家教育部科技成果鉴定 [鉴字 [教 2 0 0 2 ]第 0 0 8号 ],其主要性能指标已经达到了国际先进水平     

基于时空转换的精密位移测量新方法与传统方法的比较

回顾了时栅位移传感器原理和传统精密位移测量原理，通过比较其间细微而本质的区别，可加深对时空坐标转换方法的理解和对时栅位移传感器优势的认识。