Closed-loop control of a SCR system using a NOx sensor cross-sensitive to NH3

This paper proposes a control strategy for an automotive selective catalytic reduction (SCR) system using a NO_x sensor in a feedback loop. As is representative of real world applications, the employed NO_x sensor is cross-sensitive to NH₃, which induces several complexities. In particular the ambiguity of the measurements could be detrimental to the closed loop response, as it generates multiple equilibrium points (artefacts), besides the point of practical interest. A study of the closed-loop dynamics is performed in the vicinity of each point, which shows that the closed loop system naturally converges to the point of interest not to the artefacts. Experimental results obtained after a detailed calibration method illustrate the relevance and performance of the proposed approach.     

高压开关柜隔离触头温度监测研究

针对高压开关柜的高压、强磁场工作环境，提出了基于光纤光栅传感器的隔离触头温度测量方案，实现了高压开关柜的触头温度监测。在方案中提出了空分和波分复用的光路系统，同时采用合理的安装技术解决了应变交叉敏感的影响，通过实验建立了隔离触头温度测量模型。在突然掉电的方式下对系统的抗电磁干扰能力进行了定性分析，测量显示温度曲线是渐变而不是突变的，说明系统具有很强的抗电磁干扰能力。通过对全天温度数据监测，系统能够正常工作，说明方案是可行的。     

光纤光栅交叉敏感解决方案研究

交叉敏感问题是光纤光栅传感中的关键问题。分析了交叉敏感问题存在的物理机制,系统介绍了几种较为典型的解决方案,并提出一种新型可实现温度自补偿的光纤光栅结构克服交叉敏感问题。     

Artificial intelligence/fuzzy logic method for analysis of combined signals from heavy metal chemical sensors

The cross-sensitivity of chemical sensors for several metal ions resembles in a way the overlapping sensitivity of some biological sensors, like the optical colour receptors of human retinal cone cells. While it is difficult to assign crisp classification values to measurands based on complex overlapping sensory signals, fuzzy logic offers a possibility to mathematically model such systems. Current work goes into the direction of mixed heavy metal solutions and the combination of fuzzy logic with heavy metal-sensitive, silicon-based chemical sensors for training scenarios of arbitrary sensor/probe combinations in terms of an electronic tongue. Heavy metals play an important role in environmental analysis. As trace elements as well as water impurities released from industrial processes they occur in the environment. In this work, the development of a new fuzzy logic method based on potentiometric measurements performed with three different miniaturised chalcogenide glass sensors in different heavy metal solutions will be presented. The critical validation of the developed fuzzy logic program will be demonstrated by means of measurements in unknown single- and multi-component heavy metal solutions. Limitations of this program and a comparison between calculated and expected values in terms of analyte composition and heavy metal ion concentration will be shown and discussed.     

源于温度的电涡流传感器交叉敏感的补偿

文中在分析了高温差环境造成电涡流传感器交叉敏感的机理的基础上,以电涡流传感器在测量液态金属的电阻率过程中所出现的问题为例,提出了若干相应的补偿措施。     

On the design and analysis of an octagonal–ellipse ring based cutting force measuring transducer

This paper presents study of design, modelling, and analysis of a modified octagonal ring based cutting force measuring transducer. The shape of an octagonal ring was modified by altering the geometry of the circle into an ellipse. The main objective is to increase the strain to the displacement ratio under a given load so that the sensitivity is maximized.Analytical and three-dimensional (3D) finite element (FE) methods were deployed to estimate mechanical responses such as strain, displacement, and stress of the transducer. Results showed that compared to the octagonal ring with circle, the modified octagonal ring with ellipse had maximized the sensitivity by 15% and 25% in axial and tangential loading, respectively.In order to assess the performance of the designed transducer, calibration tests were performed on an Instron machine under axial and tangential loading and cross-sensitivity of force measurements was analysed. Following the ISO 376:2011 standard, an extensive uncertainty evaluation was performed to validate the measurement process used in the calibration.Calibration results showed that the force transducer with the proposed octagonal–ellipse ring was able to measure the force with average error less than 2%. The maximum average error in cross-sensitivity is found to be less than 5% while the overall uncertainty in measurements was up to 1.78%.Based on simulation and calibration test results, the position and the orientation of the strain gauges on the transducer were determined, and a new and compact layout of the 3D cutting force measurement system for milling was then designed and modelled. A frequency analysis was performed to assess the vibrational response of the system. It is expected that the transducer integrated with octagonal–ellipse rings would potentially be a sustainable and cheaper option for small-to-medium sized workshops to accurately measure the milling forces.     

Evaluation of selectivity of commercial hydrogen sensors

The development of reliable hydrogen sensors is crucial for the safe use of hydrogen. One of the main concerns of end users is sensor reliability in the presence of species other than the target gas, which can lead to false alarms or undetected harmful situations. To assess the selectivity of commercial-off-the-shelf hydrogen sensors, a number of sensors of different technology types were exposed to various interferent gas species. Cross-sensitivity tests were performed in accordance with the recommendations of ISO 26142:2010, using the hydrogen sensor testing facilities of the National Renewable Energy Laboratory and the Joint Research Centre – Institute for Energy and Transport. Most of the sensor platform tested are unaffected by the exposure to the interferents. The metal-oxide and the thermal conductivity platform show a remarkable sensitivity to CH₄. None of the platforms tested were permanently affected by the exposure to the cross-sensitive species.     

Cross-sensitivity of Fiber Grating Solved by FFP Triangle Notch Filter

Employing a fiber Fabry-Perot (FFP) interferometer has been considered as a triangle notch filter to demodulate the wavelength of fiber Bragg grating (FBG) sensor. The single parameter of strain has been demodulated, and the cross-sensitivity influence of temperature has been eliminated. The principle of this method is simple and easy to be implemented, and has been used to design a 30 t fiber grating weightbridge successfully. The maximal temperature drift error of the weightbridge is 4με, which means that the full scale error is 8‰. The result reveals that the accuracy is high enough to be used in measurement.     

Cross-sensitivity evaluation for ammonia sensing using absorption spectroscopy in the UV region

This paper describes an optical sensor for the monitoring of ammonia gas. An open path optical technique is used to analyze the absorption lines of ammonia within the ultra-violet region. The optical sensor shows absorption lines comparable to the theoretical ammonia spectra. Cross-sensitivity with carbon dioxide and oxygen gas has been tested and clearly shows that these two gases have no effect on ammonia measurement in the ultra-violet region, between 200 nm and 230 nm. The optical sensor is able to detect ammonia down to 9 ppm with an average error less than 2%. The optical sensor system also shows a fast response time which is less than 4 s.