Control System Design and Implementation at Flexible, Distributed Offshore Sensor Test Sites in the Yangtze Estuary Area

Marine in situ testing is a necessary step for stereotyping newly developed marine sensors. The use of test sites in the Yangtze Estuary area, which has high turbidity and abundant nutrients, can effectively reduce the needed testing time owing to its harsh conditions. Five test stations were established, and a floating buoy and fixed test equipment were designed. A control system, including a sensor connection, data processor, video remote transmission, and corresponding control algorithm, was developed. The control system enabled the nondestructive monitoring of biological attachments and bidirectional, real-time communication between an upper server on land and the control system at the test sites. The dissolved oxygen(DO), temperature, and pH data of DOS600 and DPS600 sensors were compared with those of AP2000 sensors. Temperature recording using the DOS600 sensor was performed nearly as well as that of the AP2000 sensor. The mean DO values(standard deviations) were 8.414 mg L-1(2.068) and 6.896 mg L-1(1.235) for the DOS600 and AP2000 sensors, respectively, indicating that the DOS600 performance was unsatisfactory. The pH recording of the DPS600 was slightly worse than that of the AP2000 sensor. Experimental results showed that the DO value was more easily affected by the buoy movement of waves compared to the pH and temperature. Moreover, data fluctuations showed that the DO and pH parameters were more vulnerable to biofouling than temperature. Waves and biofouling create a harsh test environment, and the performance difference between the developed sensors and a standard sensor can be obtained in a short time period.

Nondestructive testing method of wood moisture content based on a planar capacitance sensor model

For our research, a new hybrid experimental-computational method is presented. We applied a least squares fitting method （LSFM） to reconstruct the wood moisture content （WMC） from the data measured with a planar capacitance sensor. A boundary element method （BEM） was used to compute the relationship between capacitance and the dielectric constant. A functional relationship between MC and the dielectric constant was identified by LSFM. The agreement of this final computation result with the experimental data indicates that this method can be used to estimate the WMC quickly and effectively with engineering analysis. Compared with popular statistical methods, a large number of experiments are avoided, some costs of testing are reduced and the efficiency of testing is enhanced.

Stereoscopic Camera-Sensor Model for the Development of Highly Automated Driving Functions within a Virtual Test Environment

The need for efficient and reproducible development processes for sensor and perception systems is growing with their increased use in modern vehicles. Such processes can be achieved by using virtual test environments and virtual sensor models. In the context of this, the present paper documents the development of a sensor model for depth estimation of virtual three-dimensional scenarios. For this purpose, the geometric and algorithmic principles of stereoscopic camera systems are recreated in a virtual form. The model is implemented as a subroutine in the Epic Games Unreal Engine, which is one of the most common Game Engines. Its architecture consists of several independent procedures that enable a local depth estimation, but also a reconstruction of a whole three-dimensional scenery. In addition, a separate programme for calibrating the model is presented. In addition to the basic principles, the architecture and the implementation, this work also documents the evaluation of the model created. It is shown that the model meets specifically defined requirements for real-time capability and the accuracy of the evaluation. Thus, it is suitable for the virtual testing of common algorithms and highly automated driving functions.

Application Research of the Non-Destructive Testing Using Optical Fiber Sensor

In this paper, an optical fiber sensor is designed by using optical Faraday effect. It is composed of fiber collimator, polarizer, magneto-optical crystal and mirror. Based on the magnetic flux leakage (MFL) theory, The optical fiber sensor was placed between two permanent magnets with the N-pole. Therefore, the optical fiber sensing system was built to detect the defective ferromagnetic objects. Theoretical and experimental studies shown that the system can identify a little defects, such as irons’ blind hole (diameter φ =?3mm , depth t = 4mm?), irons’ grooves (length l= 30mm , width?ω = 10mm ), hole (φ?=?3mm ) and crackle etc. The system has the characteristics of small size, high sensitivity, fast signal response and high resolution. In terms of the defective oil and gas pipelines detection, The optical fiber sensing system is used in non-destructive testing, which will be valuable and meaningful.

Influence of differential settlement on pavement structure of widened roads based on large-scale model test

This study introduced at first the background of numerous highway widening projects that have been developed in recent years in China.Using a large ground settlement simulator and a fiber Bragg grating (FBG) strain sensor network system,a large-scale model test,with a similarity ratio of 1:2,was performed to analyze the influence of differential settlement between new and old subgrades on pavement structure under loading condition.The result shows that excessive differential settlement can cause considerable tensile strain in the pavement structure of a widened road,for which a maximum value (S) of 6 cm is recommended.Under the repetitive load,the top layers of pavement structure are subjected to the alternate action of tensile and compressive strains,which would eventually lead to a fatigue failure of the pavement.However,application of geogrid to the splice between the new and the old roads can reduce differential settlement to a limited extent.The new subgrade of a widened road is vulnerable to the influence of dynamic load transferred from the above pavement structures.While for the old subgrade,due to its comparatively high stiffness,it can well spread the load on the pavement statically or dynamically.The test also shows that application of geogrid can effectively prevent or defer the failure of pavement structure.With geogrid,the modulus of resilience of the subgrade is increased and inhomogeneous deformation can be reduced;therefore,the stress/strain distribution in pavement structure under loading condition becomes uniform.The results obtained in this context are expected to provide a helpful reference for structural design and maintenance strategy for future highway widening projects.

Effect of sensor quantity on measurement accuracy of log inner defects by using stress wave

Wood nondestructive testing （NDT） is one of the high efficient methods in utilizing wood. This paper explained the principle of log defect testing by using stress wave, and analyzed the effects of sensor quantity on defect testing results by using stress wave in terms of image fitting degree and error rate. The results showed that for logs with diameter ranging from 20 to 40 cm, at least 12 sensors were needed to meet the requirement which ensure a high testing accuracy of roughly 90% of fitness with 0.1 of error rate. And 10 sensors were recommended to judge the possible locations of defects and 6 sensors were sufficient to decide whether there were defects or not.

Optimal decision fusion given sensor rules

When all the rules of sensor decision are known, the optimal distributeddecision fusion, which relies only on the joint conditional probability densities, can be derivedfor very general decision systems. They include those systems with interdependent sensorobservations and any network structure. It is also valid for m-ary Bayesian decision problems andbinary problems under the Neyman-Pearson criterion. Local decision rules of a sensor withcommunication from other sensors that are optimal for the sensor itself are also presented, whichtake the form of a generalized likelihood ratio test. Numerical examples are given to reveal someinteresting phenomena that communication between sensors can improve performance of a senordecision, but cannot guarantee to improve the global fusion performance when sensor rules were givenbefore fusing.

非接触式R-test测量仪的现场标定方法研究

R-test测量仪是用于五轴数控机床转动轴结构误差测量的专用设备,其标定的准确性和可实施性是保证测量精度的重要前题。研究了一种采用电涡流位移传感器的非接触式R-test测量仪现场标定方法。该方法可直接在被测量机床上实施,利用机床直线轴的高精度微量移动完成仪器测量坐标系和传感器感应平面的标定。在标定完成后,通过样机的现场标定实验和精度验证,验证所提出标定方法的精度和可实施性。最后证明了该方法可减小R-test测量仪在加工装配以及在机床上安装过程所引入的误差对最终测量精度的影响,从而提高R-test测量仪的测量精度和可靠性。

一种非接触式R-test测量仪球心坐标计算方法

R-test测量仪是用于五轴数控机床转动轴结构误差测量的专用设备,其通过测量球相对测量坐标系的位置变化进行误差辨识。在测量坐标系中,测量球球心坐标计算的准确性和稳定性是保证测量精度的重要前提。为进行测量球球心坐标的精确计算,构建了非接触式R-test测量仪的结构模型并建立了球心坐标计算方程组。以球心坐标计算方程组为基础,简化得到用于球心坐标求解的非线性方程组并构建其目标函数,然后采用差分进化算法提高球心坐标求解的精度。最后,在GF Mikron UCP800五轴机床上进行对比实验,将测量球球心坐标的计算结果与机床实际坐标进行对比,验证所提出球心坐标计算方法的精度和可靠性。

非接触式R-test测量仪结构参数优化方法研究

R-test测量仪是用于五轴数控机床旋转轴结构误差测量的专用设备,其结构形式和参数决定了测量范围和可靠性。对采用电涡流位移传感器的非接触式R-test测量仪典型结构及其测量原理进行了分析。在其他元器件尺寸确定的情况下,通过优化计算R-test测量仪结构参数,包括传感器仰角α和传感器中心间距λ,实现测量仪的灵敏度和测量空间最大化,有效改善了测量仪性能。

Research on A Checking Method of Vibration Characteristics for Test System

To ensure the accuracy and precision of vibration test,a universal checking method is proposed.The use of the method is discussed and an actual example is given.First,the calibration of the 7703A-500 type sensor is analyzed on the basis of frequency response method.The frequency range of normal working can be determined by the exact calibration of sensitivity,frequency response and linearity.For the basic problem of abnormal signals appearing in test system,the method of zero check and loading vibration source are developed.The frequency spectrum of output signals is employed to distinguish the noise signal,unknown source signal and useful signal effectively.Finally,the experimental results reveal the importance to improve the accuracy of the results of practical vibration test.

Preparation and Characterization of Zireonia Oxygen Sensors

A thimble zirconia oxygen sensor electrolyte and their interface were observed with was prepared with YSZ. The surfaces of the Pt electrode, a scanning electron microscope （SEM）.The sensor was examined with engine bench test to evaluate the essential performance. The basic function such as electromotive force output and response time was discussed. The oscillograph trace was also obtained and analyzed with four different frequencies. The experimental results reveal that the oxygen sensor has high performances meeting the demands of practical applications..

Real-time quality control of data from Sea-Wing underwater glider installed with Glider Payload CTD sensor

Profiles observed by Sea-Wing underwater gliders are widely applied in scientific research. However, the quality control(QC) of these data has received little attention. The mismatch between the temperature probe and conductivity cell response times generates erroneous salinities, especially across a strong thermocline. A sensor drift may occur owing to biofouling and biocide leakage into the conductivity cell when a glider has operated for several months. It is therefore critical to design a mature real-time QC procedure and develop a toolbox for the QC of Sea-Wing glider data. On the basis of temperature and salinity profiles observed by several Sea-Wing gliders each installed with a Sea-Bird Glider Payload CTD sensor, a real-time QC method including a thermal lag correction, Argo-equivalent real-time QC tests, and a simple post-processing procedure is proposed. The method can also be adopted for Petrel gliders.

Preparation and analysis of zirconia oxygen sensors

Thimble zirconia oxygen sensors were prepared with yttria stabilized zirconia(YSZ). The surfaces of the electrode, electrolyte and their interface were observed by scanning electron microscope(SEM). The sensor was examined with engine bench test to evaluate the essential performance. The results show that the oxygen sensor has good performance, which can meet the demand of practical applications. Chemical equilibrium theory was introduced to explain electromotive force of the sensors and the influence of temperature on the signals. The educed theoretical model of electromotive force agrees well with testing results.

二维低频光纤布拉格光栅振动传感器的设计

本文设计了一种可在x轴和z轴方向工作的对称圆形柔性铰链式二维振动传感器,以对低频振动信号进行获取和监测。从理论上分析了传感结构的力学特性,在Comsol中建立模型进行仿真分析,并采用有限元法对结构进行优化设计,将铰链谐振频率设计为420 Hz。采用光纤布拉格光栅(FBG)作为应变检测器件粘贴在铰链结构表面,利用边沿滤波器法实现FBG的动态解调,采用标准振动台对传感器性能进行测试。实验结果表明该传感器在x轴和z轴的谐振频率为420 Hz,工作频率为20~300 Hz。在平坦区的平均灵敏度为1847.32 mV/g,加速度分辨率达5.41×10^(-4)g。该传感器在所有二维方向上的横向干扰水平均小于5%。本文设计的传感器为二维振动传感器,可适用于低频振动信号的高灵敏检测。

Force/Moment Isotropy of 8/4-4 Parallel Six-Axis Force Sensor Based on Performance Atlases

A six-axis force sensor with parallel 8/4-4 structure is introduced and its measurement principle is analyzed.Based on condition numbers of Jacobian matrix spectral norm of the sensor,the relationship between the force and moment isotropy and some structural parameters is deduced.Orthogonal test methods are used to determine the degree of primary and secondary factors that have significant effect on sensor characteristics.Furthermore,the relationship between each performance index and the structural parameters of the sensor is analyzed by the method of the atlas,which lays a foundation for structural optimization design of the force sensor.

Crack Length Quantification Based on Planar Eddy-Current Sensor Array and Two-Dimensional Image

Eddy-current (EC) testing is an effective electromagnetic non-destructive testing (NDT) technique.Planar eddy-current sensor arrays have several advantages such as good coherence,fast response speed,and high sensitivity,which can be used for micro-damage inspection of crucial parts in mechanical equipments and aerospace aviation.The main purpose of this research is to detect the defect in a metallic material surface and identify the length of a crack using planar eddy-current sensor arrays in different directions.The principle and characteristics of planar eddy-current sensor arrays are introduced,and a crack length quantification algorithm in different directions is investigated.A damage quantitative detection system is established based on a field programmable gate array and ARM processor.The system is utilized to inspect the micro defect in a metallic material,which is carved to micro crack with size of 7mm(length)×0.1mm(width)×1mm(depth).The experimental data show that the sensor arrays can be used for the length measurement repeatedly,and that the uncertainty of the length measurement is below ±0.2mm.

Optimal sensor placement in hydropower house based on improved triaxial effective independence method

The capacity and size of hydro-generator units are increasing with the rapid development of hydroelectric enterprises, and the vibration of the powerhouse structure has increasingly become a major problem. Field testing is an important method for research on dynamic identification and vibration mechanisms. Research on optimal sensor placement has become a very important topic due to the need to obtain effective testing information from limited test resources. To overcome inadequacies of the present methods, this paper puts forward the triaxial effective independence driving-point residue （EfI3-DPR3） method for optimal sensor placement. The Efl3-DPR3 method can incorporate both the maximum triaxial modal kinetic energy and linear independence of the triaxial target modes at the selected nodes. It was applied to the optimal placement oftriaxial sensors for vibration testing in a hydropower house, and satisfactory results were obtained. This method can provide some guidance for optimal placement of triaxial sensors of underground powerhouses.

Experimental Verification and Research for the Distortion in the Integrated Frequency Responses of the High-Pressure Sealed Cabin and Magnetic Field Sensor

Although magnetotelluric sounding method applied to the land is advanced, there are many difficulties when it is applied to marine environment, one of which is how to lay magnetic field sensors down to the seafloor to complete measurements. To protect the magnetic field sensors from intense erosion and high pressure, suitable high-pressure sealed cabins must be designed to load them. For the consideration of magnetic measurement and marine operation, the sealed pressure cabin should be nonmagnetic and transportable. Among all optional materials, LC4 super.hard aluminum alloy has the highest performance of price/quality ratio to make the sealed pressure cabin. However, it does not mean that the high-pressure sealed cabin made using LC4 will be perfect in performance. In fact, because of its weak magnetism, the pressure cabin made using LC4 has distorting effect on frequency responses of the magnetic field sensors sealed in it. This distorting effect does not affect the use of the magnetic field sensor, but if we want to eliminate its effect, we should study it by experimental measurements. In our experiment tests, frequency sweep magnetic field as excitation signal was used, and then responses of the magnetic field sensor before and after being loaded into the high-pressure sealed cabin were measured. Finally, normalized abnormal curves for the frequency responses were obtained, through which we could show how the high-pressure sealed cabin produces effects on the responses of the magnetic field sensor. Experimental results suggest that the response distortion induced by the sealed pressure cabin appears on mid- and high-frequency areas. Using experimental results as standardization data, the frequency responses collected from seafloor magnetotelluric measurements can be corrected to restore real information about the seafloor field source.

CMOS图像传感器辐射敏感参数测试电路设计及试验验证

以航天领域广泛应用的CMV4000型CMOS图像传感器(CIS)为研究对象,通过开展CIS辐射敏感参数测试电路设计,将CIS辐照电路板与测试电路板中FPGA数据采集及传输板分离,辐照电路板与测试电路板通过接插口通信,从而实现开展辐照试验时对FPGA数据采集部分进行辐射屏蔽防护,避免FPGA数据采集板受到辐射影响。开展了CIS测试电路中的电源模块、数据采集、存储模块、外围电路等设计及PCB版图的布局布线设计。采用VerilogHDL硬件描述语言对各个功能模块进行驱动时序设计,实现CIS辐射敏感参数测试功能。通过开展CMV4000型CIS ^(60)Coγ射线辐照试验,分析了平均暗信号、暗信号非均匀性、暗信号分布等辐射敏感参数随总剂量增大的退化规律,验证了CIS辐射敏感参数测试系统的可靠性。