Industrial liquid characterization enhancement using microwave sensor equipped with electronic band gap structure

In this paper, we present a novel sensor for permittivity measurement of the industrial liquids to achieve more sensitivity. An electronic band gap (EBG) structure is used. The simulation results show that applying EBG scheme enhances the electric field strength at the measuring part. This issue causes a significant shift in resonant frequency and therefore an increased sensitivity of the designed sensor. The proposed sensor is tested for characterization of liquids with various permittivity and loss tangent values, and the results show the proposed sensor can precisely classify a wide range of liquids in terms of electromagnetic properties. Measurement results indicate that the presented sensor is well suited for transformer oil aging applications.     

液相化学反应介电常数的测量与气泡影响分析

溶液中化学反应的等效介电常数是微波化学研究中的重要内容,等效介电常数的精确测量是研究微波与化学反应系统相互作用的基础.介绍了一种对溶液中化学反应等效介电常数随时间微弱变化跟踪测量的方法并对测量中经常遇到的气泡影响进行了分析.最后制作了一批测量探头,该探头可以有效排除其中的气泡.通过测量得到的反射系数和遗传算法(GA)可以对等效介电常数的微小变化进行精确测量.对稀溶液中的皂化反应测量的结果证实了该测量方法的有效性.     

A new tool for accurate S-parameters measurements and permittivity reconstruction

In this paper, we present a tool for permittivity reconstruction. The tool consists of a coaxial transmission line and a novel analytical reconstruction technique. The line is designed for accurate permittivity measurements of soil samples. It allows for single or double phase flow. The full S-parameter matrix is modeled with transmission line theory. We show that for accurate measurements each component of the tool needs careful calibration. We give a method to compute the sensitivity of these measurements to different materials, and we show the accuracy in the determination of the sample permittivity from the measurements based on deviations of the forward model compared to measured results as a function of the error in the sample permittivity. We demonstrate that a maximum error of less than 1% is obtained for the possible permittivity reconstruction from these measurements for wavelengths less than five times the sample holder length. The novel reconstruction technique is based in the propagation matrices method. It consists in rewriting the transmission line model in matrix notation and relating the S-parameters to the total reflection and transmission of the line seen as a two-port network. Thanks to this novel approach, the reconstruction of both permittivity and permeability can be done directly from the measured S-parameters of the line. Due to experimental instabilities the errors are considerable, and we must restrict ourselves to the reconstruction of permittivity. Results on an air sample are within the predicted error of 1%. Computing relative errors for an ethanol sample is not possible due to temperature and purity difference between our experiment and published results; nevertheless, the reconstructed permittivity of ethanol follows the Debye model.     

Compact substrate integrated waveguide sensor for liquids permittivity measurement

A compact substrate integrated waveguide (SIW) liquids permittivity sensor structure that utilizes half-mode (HM) and slow-wave (SW) techniques for the miniaturization of SIW sensor is presented in this paper. First, HM miniaturization technique is applied to SIW resonator cavity. Sensor width is reduced by 50% in comparison to the conventional resonator. Due to the complexity of the relationship between the complex permittivity of the substrate and liquids under test, artificial neural network tool is used as a simple and fast method to determine liquids’ complex permittivity through the measured resonant frequency and unloaded quality factor. The sensor is fabricated, and good agreement with simulations is observed according to the obtained experimental results. In the second step, SW and HM techniques are applied to the SIW sensor. The application of the HM and SW techniques indicate that an increase in sensor miniaturization while obtaining a better quality factor could be achieved. Furthermore, HM-SW-SIW is not fabricated, and we are satisfied with simulation results since we have fabricated other components. Moreover, good correspondence between the measurement and simulation results is obtained. Finally, a comparison between the structures presented in this paper and those published previously is made, demonstrating that a minimum of 25% miniaturization is achieved while maintaining acceptable characteristics.     

Optical Fiber Type Slide Tactile Sensor Used for Underwater Robot

Bexause of the special underwater environment, many sensors used well in robots working in space or on the hand can not be used in the underwater.So an optical fiber type slide tactile sensor is designed by the inner modulation mechanism of the intensity type optical fiber.The principle and structure of the sensor are introduced in detail.The static and dynamic characteristics are analyzed theoretically and experimentally.The dynamic characteristic model is built and the simulation is made by using genetic algorithm based on neural network.In order to use the sensor perfectly, the recognition model of the sensor is built on the basis of the principle of “inverse solution”using neural networks.The control precision and sensitivity of the manipulator are improved.     

一种基于CMOS的高集成度太赫兹近场传感器

为了解决太赫兹波段近场传感器分辨率低和成本高的问题,提出了一种高图像分辨率、高集成度的传感器设计方案.该330 GHz传感器基于55 nm互补金属氧化物半导体（complementary metal oxide semiconductor,CMOS）工艺仿真实现,由330~336 GHz调谐范围的单端输出环形振荡器、宽带谐振器和功率探测器在单一硅片下集成.仿真结果表明,环形振荡器在偏置电压为2 V时达到峰值输出功率0.9 dBm@330 GHz,即1.23 mW.根据振荡器调谐范围,设计了一个宽带谐振器用于对待测物进行近场感测,通过放置不同介电常数的物体于其顶端表面,再通过探测器读出输出电压,与未放置物体时探测器的输出电压的差值即为该传感器的响应.此单片集成的传感器可以在单片上实现太赫兹照明、探测、传感以及成像功能,在未来太赫兹近场成像领域有较强的应用潜力.     

基于光纤光栅的机器人腕部多维力传感器

为实现机器人腕部等关节受力情况的测量,设计了一种十字型光纤光栅多维力传感器,该传感器由两个圆环及两环间呈90°分布的四个相同的等截面悬臂梁及粘贴于其上的光纤光栅组成.分析了传感器的传感原理并使用ANSYS对传感器进行力学仿真分析;研究了传感器不同部位受力时悬臂梁的应变情况;搭建了实验平台,进行了传感器的标定实验和温度补偿研究;通过对仿真数据和试验结果进行数学分析,得出了光纤光栅中心波长漂移量与传感器的受力关系.实验结果显示,该传感器能准确地测量腕部所受力的大小和位置,误差在1.6％以内,且抗干扰能力强,具有较好的稳定性,能在复杂环境中使用.     

基于支持向量机的介质圆柱体逆散射问题研究

提出一种新的在线逆散射方法-支持向量机,通过支持向量机将原问题转化成一个回归估计问题.该方法可广泛应用于各种逆散射方面,尤其是目标的几何与电磁参数重构.以相对介电常数作为输入,复散射系数作为输出,通过对训练样本的学习,利用支持向量机回归估计了介质圆柱体不同相对介电常数下复散射系数的实部与虚部.同时,以多个观测点的散射电场值作为样本信息,利用支持向量机对已知探测范围内的介质圆柱体的相对介电常数和电导率进行了重构.比较结果显示了该方法的有效性和准确性.     

一种基于神经网络的复介电常数测量装置

物质的复介电常数反映了物质对微波的吸收和透射能力,为了提高微波工业应用中能量的利用效率,能准确测量物质的介电常数就显得尤为重要.本文设计了一种在2.45 GHz下的单端口圆柱腔体测量装置,内置聚四氟乙烯容器放置待测物质,避免化学溶液与腔体的金属发生反应影响测量准确性.使用圆形贴片天线向腔体内馈波,提高物质吸收微波的均匀...     

Numerical Analysis of Open-Ended Coaxial Lines

Numercal methods are applied in the analysis of coaxial structures used as sensors for in vivo permittivity studies of biological substances. The methods used for the solution of the resulting static conductor-dielectric problems are the Finite Element Method (FEM) and the Method of Moments (MOM) applied to a pair of coupled integral equations. A linear model which relates the sample permittivity to the fringing field capacitance of the sensor is discussed and values of the model parameters are calculated for different types of sensors.     

Practical aspects of complex permittivity reconstruction with neural-network-controlled FDTD modeling of a two-port fixture.

The paper discusses characteristics of a new modeling-based technique for determining dielectric properties of materials. Complex permittivity is found with an optimization algorithm designed to match complex S-parameters obtained from measurements and from 3D FDTD simulation. The method is developed on a two-port (waveguide-type) fixture and deals with complex reflection and transmission characteristics at the frequency of interest. A computational part is constructed as an inverse-RBF-network-based procedure that reconstructs dielectric constant and the loss factor of the sample from the FDTD modeling data sets and the measured reflection and transmission coefficients.As such, it is applicable to samples and cavities of arbitrary configurations provided that the geometry of the experimental setup is adequately represented by the FDTD model. The practical implementation of the method considered in this paper is a section of a WR975 waveguide containing a sample of a liquid in a cylindrical cutout of a rectangular Teflon cup. The method is run in two stages and employs two databases--first, built for a sparse grid on the complex permittivity plane, in order to locate a domain with an anticipated solution and, second, made as a denser grid covering the determined domain, for finding an exact location of the complex permittivity point. Numerical tests demonstrate that the computational part of the method is highly accurate even when the modeling data is represented by relatively small data sets. When working with reflection and transmission coefficients measured in an actual experimental fixture and reconstructing a low dielectric constant and the loss factor the technique may be less accurate. It is shown that the employed neural network is capable of finding complex permittivity of the sample when experimental data on the reflection and transmission coefficients are numerically dispersive (noise-contaminated). A special modeling test is proposed for validating the results; it confirms that the values of complex permittivity for several liquids (including salt water acetone and three types of alcohol) at 915 MHz are reconstructed with satisfactory accuracy.     

基于Hilbert分形结构的电子标签天线设计研究

基于分形理论思路,设计了一款Hilbert分形结构的无源电子标签天线,分析研究了天线基板材料和封装材料的相对介电常数大小与介质厚度对天线性能的影响。仿真结果表明:随着介质厚度和材料相对介电常数的增加,谐振频率下降,但是对第一谐振频率点的方向图影响不大。这在电子标签的设计、仿真和制作中具有重要的参考意义。     

Ultra Wide Band (UWB) Horseshoe Antenna for Future Cognitive Radio Applications

In this paper, an UWB micro-strip antenna design has been proposed which is suitable for future cognitive radio applications. The geometry of proposed antenna is composed of two semi-circles with their interior modified in order to achieve higher impedance bandwidth. The semi-etched ground provides further bandwidth enhancement. The proposed antenna is fabricated on an inexpensive dielectric substrate FR-4 with relative permittivity of 4.4 and thickness of 1.6 mm. The overall dimensions of UWB antenna are 60?×?60?×?1.6 mm and have a bandwidth of 5.7 GHz. The designed antenna covers the most commonly used wireless communication bands such as DCS-1800, ISM bands, GPS, Wi-MAX, WLAN, 3G, 4G, etc. The design process and the variations in antenna’s performance due to different parameters has been discussed. The design and simulation of the antenna are carried out in the Ansys Electronic Desktop HFSS. The measured results are in good agreement with simulated results and design theory which shows that the proposed antenna is good candidate for the UWB applications.

     

Measurement/computation of effective permittivity of dilute solution in saponification reaction

For better application of microwaves in chemistry, the interaction between microwaves and the chemical reaction needs further study. Since the reactants form a complicated mixture, which changes with time, an effective permittivity can be used to describe the molecular polarization of the mixture in the reaction. The effective permittivity is expected to change with microwave frequency, temperature and reaction time. However, in many cases, the change of effective permittivity in a saponification reaction is too small to be detected using traditional methods. In this paper, we present a hybrid experimental/computational method for determining the effective permittivity in a saponification reaction. We use a resonant coaxial sensor to measure the reflection coefficients. To predict its performance, the electromagnetic-field distribution near the sensor and the reflection coefficient are calculated employing a frequency-dependent finite-difference time-domain method. Next, we develop a genetic-algorithm-based inverse-calculation technique and employ it to determine the complex permittivity of pure water from the measured reflection coefficient and compare the results with those obtained from Debye's equation. Finally, the hybrid experimental/computational method is employed to determine the effective permittivity of a dilute solution in a typical saponification reaction. Results are presented and discussed.     

High performance read-out IC design for IR image sensor applications

In this paper, high performance read-out integrated circuits (ROIC) for infrared (IR) image sensor applications is proposed. Because an uncooled microbolometer image sensor, used in an IR image sensor, is made by a micro electro mechanical systems process, the resistance of bolometer by each process does not appear same value under same temperature condition. This resistance variation generates a different output signal for same input by each chip. In order to improve on these drawbacks, a ROIC, which compensates for the error described above, was designed. Instead of a single input mode, a differential input mode ROIC was proposed and thus, a new circuit structure was proposed. Using results from a computer simulation, improvements such as that the effect of the process error was decreased 10–12% without an additional compensation circuit was found. Based on the simulation results, a prototype device including a ROIC and a micro bolometer with 16 × 16 cell arrays was fabricated and characterized.     

A novel area efficient on-chip RO-Sensor for recycled IC detection

Out of different types of counterfeit integrated circuits (ICs) present in the supply chain, recycled ICs are major threat to security and reliability of electronic components. Recycled ICs possess shorter lifetime and it is extremely difficult to distinguish a recycled IC in a group of fresh IC with similar functionality. Out of several recycled IC detection methodology, Ring Oscillator (RO) sensor based detection approach is most efficient, because of its simple design and can detect ICs used only for few days. In this paper, we proposed two different types of modified RO sensor with lower area overhead. First RO sensor accelerates the aging to improve the detection of recycled ICs which are used for few days. The second architecture uses current controlled configurable RO (C-CRO) to further improve the detection of recycled IC. The RO in both the proposed sensor is designed by using modified pseudo NMOS logic based inverter. The proposed inverter accelerates the aging caused by negative bias temperature instability (NBTI) and lower the impact of process variation (PV) to improve the rate of detection. Both the proposed RO sensors are simulated in 90 nm CMOS technology. The simulation result shows both the proposed sensor improves the rate of detection as compared to the conventional sensor.     

光学电压互感器晶体双折射误差的分析与抑制

锗酸铋(BGO)晶体的双折射误差极大地制约着准互易反射式光学电压互感器(OVS)的精度。根据各光学元器件的参数,建立了各器件的琼斯矩阵以及光路系统的数学模型。在此模型基础上,仿真计算了晶体双折射误差对系统性能的影响;提出了晶体应力双折射对系统输出偏置的影响可以通过滤波算法进行抑制的方法,并设计了一个高通滤波器对数字输出进行抑制。实验结果表明,加入高通滤波器不改变光学电压互感器静态特性,抑制了晶体双折射引起的输出漂移,提高了互感器的测量精度。     

最小误差空域预滤波矩阵求解及误差分析

建立了空域矩阵滤波器设计最优化问题,利用两种方法给出该最优化问题的最优解。第一种方法是通过将最优化问题转化为以向量为未知数的另一个最优化问题,并求解稳定点,重排获得原问题的最优解。第二种方法是利用对原最优化问题求偏导数的方式,直接获得最优解。利用广义奇异值分解,给出了最优解的简化形式。通过仿真,给出了不同阵元数情况下,预滤波的响应效果,通过对比可知,与恒定阻带抑制滤波器相比,最小误差空域预滤波矩阵有更小的归一化响应误差。     

电解质溶液复介电常数测量中金属杂质的影响

为了克服金属杂质对电解质溶液复介电常数测量结果的影响，分别对不同位置与数量的金属杂质对氯化钠溶液复介电常数测量的影响进行了数值分析。计算结果表明：金属杂质对电解质溶液复介电常数测量值的实部影响很小，而对虚部影响较大，且金属杂质对虚部的影响随着探头表面的金属杂质数量的增加而增大。     

传感网中基于压缩感知的丢包匹配数据收集算法

为了提高传感网中数据重构精度以及降低不可靠链路丢包对压缩感知（Compressive Sensing，CS） 数据收集的影响，本文提出了一种基于压缩感知丢包匹配数据收集算法（Packet Loss Matching Data Gathering Algorithm Based on Compressive Sensing，CS-MDGA）.本文算法通过压缩感知技术构建了全网数据间的"关联效应"，并设计了基于丢包匹配的稀疏观测矩阵（Sparse Observation Matrix Based on Packet Loss Matching，SPLM），证明了该观测矩阵概率趋近于"1"时，满足的等距约束条件（Restricted Isometry Property，RIP），完成了节点间多路径路由数据的可靠交付.仿真实验结果表明，本文算法在链路丢包率为60%情况下，相对重构误差仍小于5%，验证了本文算法不仅具有较高的重构精度，而且还可以有效缓解不可靠链路丢包对CS数据收集的影响.