A Magnetic Null-Balance Displacement Measuring System Using Radio-Frequency Modulation

Magnetic null-balance and a unique magnetic method of radio-frequency modulation combine to relate an electrical output precisely to the displacement of a small permanent magnet probe. The magnetic null-balance eliminates undesirable effects of magnetic material characteristics, and the use of a radio-frequency carrier provides large stabilizing gain with simple circuitry. The electrical analog output is derived by demodulation and filtering so that it contains only the frequency components of the measured displacement. Precise linearity between the displacement and the output is insured by the large amount of over-all dc negative feedback and by adherence to geometrical criteria developed for the displacement sensor. Static and dynamic tests of several of the measuring systems designed to produce 0-4 ma signals in response to 0-0.100-inch displacements have shown gratifyingly small errors, verifying the design expectations.     

Application of Super-High Frequency Doppler Displacement Sensors in an Anti-Lock Braking System

Measurement Techniques - Issues in the optimization of the operation of the anti-lock braking system of a vehicle are examined. In order to enhance the reliability of system operation, it is...     

Continuous Terrestrial Positioning Based on Microwave Displacement Sensors

Measurement Techniques - An autonomous positioning system is proposed for navigation of terrestrial transport based on microwave radar displacement sensors. An algorithm for direct and continuous...     

一种位移传感器校准装置

发电机组安全监测系统(TSI)中使用到许多位移传感器,市场上没有一种现成的可利用的自动化程度高的校验标准设备。为了实现位移传感器的量值溯源,研制一种位移传感器自动校准装置。实验证明,本装置满足多类型位移传感器的校准需求,填补了TSI领域位移传感器校验标准的空白,具有较好的应用前景。     

基于线阵 CCD 的全息光栅位移传感器

目的：提出了一种新型的基于全息光栅的CCD位移传感器。方法：利用CCD分辨率高，像素均匀等特点，对干涉条纹的移动进行精确定位，利用全息光栅在测量过程中又具有不受光源波长的影响，适用光谱范围宽等特点，实现位移的自动精确测量。结果：系统能够对位移实现自动精确测量。结论：该系统具有一定的实用价值及应用前景。     

基于光纤布喇格光栅传感器的精密位移测量

首先对光纤布喇格光栅传感的基本原理进行了分析,并给出了光纤光栅位移传感的基本公式.在此基础上,设计制作了一种光纤光栅位移传感器.采用光纤光栅作为传感元件,利用多波长计进行波长检测,对位移量进行了传感测量.实验中,传感器位移检测范围为0.6mm,其传感测量精度为±43nm,测量分辨率为1.5nm.实验结果具有良好的线性度.     

A Multimodal Tomography System Based on ECT Sensors

A new noninvasive system for multimodal electrical tomography based on electrical capacitance tomography (ECT) sensor hardware is proposed. Quasistatic electromagnetic fields are produced by ECT sensors and used for interrogating the sensing domain. The new system is noninvasive and based on capacitance measurements for permittivity and power balance measurements for conductivity (impedance) imaging. A dual sensitivity map of perturbations in permittivity and conductivity is constructed. The measured data along with the sensitivity matrix are used for the actual image reconstruction. The new multimodal tomography system has the advantage of using already established reconstruction techniques, and the potential for combination with new reconstruction techniques by taking advantage of combined conductivity/permittivity data. Moreover, it does not require direct contact between the sensor and the region of interest. The system performance has been tested on representative data, producing good results     

Analytic Thermal Modeling for dc-to-Midrange Modulation Frequency Responses of Thin-Film High- T c Superconductive Edge-Transition Bolometers

Thin-film superconductive edge-transition bolometers are modeled with a one-dimensional analytic thermal model with joule heating, film and substrate materials, and the physical interface effects taken into consideration. The results from the model agree well with the experimental results of samples made of large-meander-line Yba(2)Cu(3)O(7-x) films on crystalline SrTiO(3), LaAlO(3), and MgO substrates up to 100 kHz, the limits of the experimental setup. Compared with the results of the SrTiO(3) substrate samples, the results from the model of the LaAlO(3) and the MgO substrate samples deviate slightly from the measured values at very low modulation frequencies (below ~10 Hz). The deviation increases for higher thermal-conductive substrate materials. When the model was used, the substrate absorption and the thermal parameters of the devices could also be investigated.     

反射光学式位移检测系统

系统由半导体激光器、聚焦镜头、反射式标尺光栅、四裂相指示光栅和光电接收元件组成。该系统具有光学两倍频作用和大光栅副间隙下使用及间隙对莫尔条纹信号调制度不敏感等特点,并且整体结构分离式、小型化和轻型化,在各类精密测量装置和精密加工仪器中将得到越来越广泛的应用。本文介绍这种反射光学式位移检测系统的结构原理,系统特点和应用。     

A Wireless Pharmaceutical Compliance Monitoring System Based on Magneto-Inductive Sensors

We have developed a magnetic sensor-based wireless pharmaceutical compliance monitoring (PCM) system using an array of magneto-inductive sensors mounted around the patient's neck in the form of a tight necklace. This system detects the passage of a pill or capsule embedded with a small permanent magnet as a tracer through the esophagus upon ingestion. As a result, a signal representing a ldquodose ingestion eventrdquo is generated and wirelessly transmitted to a data delivery device (PDA), which is carried on the patient's body. A software application running on the PDA time/date stamps the event and stores it for later retrieval by a physician. This technology provides a safe, convenient, low-cost, and accurate detection mechanism that helps patients adhere with their prescribed medication regimens. It also helps researchers and pharmaceutical companies conduct more accurate clinical trials on new drugs. A proof-of-concept prototype system using off-the-shelf components and custom PCB has been developed and successfully tested. Preliminary results using an artificial neck showed 94.4% correct detections when the magnetic tracer passed through the detection zone and about 6% false positives for outside areas.     

一种基于光拍频的连续激光调制光谱测量方法

针对F-P干涉仪分析连续激光调制光谱的局限性,本文提出了一种基于光拍频的连续激光调制光谱的测量方法,该方法可实现调制频率低达千赫兹的连续激光调制光谱的测量.本方法以光电转换理论为基础,利用频谱分析仪测得参考光与连续调制光谱的拍频信号,然后通过相应的数学计算得到连续调制光谱的各个光频的相对电场强度,从而实现连续调制光谱的分析.本文在理论建模与分析的基础上,利用该方法对半导体激光器出射激光经电光调制器调制产生的调制光谱进行了测量,测量结果与F-P干涉仪测量结果一致,验证了该方法的可行性.     

基于线性调频技术的超声波测波方法

线性调频相关技术在超声波测波仪中的应用大大提高了测波仪测量精度和分辨力,解决了其在大风浪或近岸破碎波的情况下测量误差过大或检测不到回波的难题.本文阐述了基于线性调频技术的超声波测波原理以及线性调频信号的设计,进行了调频信号相关性分析,并基于该技术设计了测波系统.通过模拟波浪实验对系统的性能、波浪数据的质量进行了验证,结果表明:在大风浪情况下采集到的原始数据未出现丢失现象,1/3波高的误差为5 cm.实验结果证明所研发的测波系统精确度高,适合近岸观测波浪.     

Gold Nanoparticle‐Based Sensors Activated by External Radio Frequency Fields

A novel molecular beacon (a nanomachine) is constructed that can be actuated by a radio frequency (RF) field. The nanomachine consists of the following elements arranged in molecular beacon configuration: a gold nanoparticle that acts both as quencher for fluorescence and a localized heat source; one reporter fluorochrome, and; a piece of DNA as a hinge and recognition sequence. When the nanomachines are irradiated with a 3 GHz RF field the fluorescence signal increases due to melting of the stem of the molecular beacon. A control experiment, performed using molecular beacons synthesized by substituting the gold nanoparticle by an organic quencher, shows no increase in fluorescence signal when exposed to the RF field. It may therefore be concluded that the increased fluorescence for the gold nanoparticle‐conjugated nanomachines is not due to bulk heating of the solution, but is caused by the presence of the gold nanoparticles and their interaction with the RF field; however, existing models for heating of gold nanoparticles in a RF field are unable to explain the experimental results. Due to the biocompatibility of the construct and RF treatment, the nanomachines may possibly be used inside living cells. In a separate experiment a substantial increase in the dielectric losses can be detected in a RF waveguide setup coupled to a microfluidic channel when gold nanoparticles are added to a low RF loss liquid. This work sheds some light on RF heating of gold nanoparticles, which is a subject of significant controversy in the literature.     

Frequency Modulated Continuous Wave System for Optical Fiber Intensity Sensors With Optical Amplification

We report on the use of erbium doped fiber (EDF) amplification to enhance a frequency modulated continuous wave (FMCW) technique for referencing optical intensity sensors located between two Bragg grating structures. The experiment combines the concept of FMCW with the spectrally selective mirror properties of Bragg gratings to interrogate with referencing properties intensity based sensors. The interrogation system without amplification yields a sensor resolution of around 0.078 dB. When the EDF amplifier is introduced into the experimental set up, the sensor sensitivity does not change, but the signal-to-noise ratio is improved, resulting into an enhanced resolution of 0.025 dB. We also obtain a remote sensing operation at a location of 50 km, showing the feasibility of this configuration to be used as a remote sensing application.     

基于MEMS惯性传感器的微型姿态测量系统

提出了一种基于低成本MEMS惯性传感器的微型姿态测量系统,包括MEMS速率陀螺、MEMS磁强计、单轴MEMS加速度传感器.重点研究了基于扩展Kalman滤波（EKF）的姿态估计创新算法,通过速率陀螺更新误差状态四元数计算姿态角,并通过飞行方向的加速度传感器和三轴磁强计来补偿陀螺漂移和姿态角误差,利用扩展卡尔曼滤波方程消除瞬时干扰,实现高动态姿态测量.系统的仿真和高动态实验表明,姿态测量动态精度低于5°,静态精度低于0.7°.     

Continuous-Flow System for On-Line Water Monitoring Using Back-Side Contact ISFET-Based Sensors

A multiparametric continuous-flow system for on-line monitoring of water based on ISFET sensors is described. The ISFETs used have silicon nitride as gate material, and the electrical contacts are placed on the back side of the chip. This is a technological improvement that allows for a more compact ISFET packaging and greatly increases the lifetime of the sensor compared with planar type ISFETs, since the electrical parts are separated from the chemical environment. A special probe has been designed in order to encapsulate and apply these ISFETs into the flow system. Further, a reference electrode based on standard Ag/AgCl technology has been constructed according to the ISFET probe design in order to integrate both sensors in the same flow-through cell. These probes can be easily replaced in the flow system and are made of cheap and easily mechanized materials. Using these flow-through sensors, a continuous-flow system for the determination of pH, NH(4)(+), Ca(2+), and NO(3)(-) in waters has been designed. The system configuration is based on a modular design (one setup for each parameter and a common sampling channel), which allows simple manipulation and maintenance as well as a good flexibility for different analytical requirements. A study of the system characteristics was performed by following the specifications for water monitoring. Under the conditions established for the flow system, a sampling rate of 20 h(-)(1) was obtained for each parameter, and long-term stabilities of at least 3 weeks of daily work for ISFET sensors and 5 months for the reference electrode have been achieved. The response performances obtained show the feasibility of the BSC ISFET probe use in continuous-flow monitoring.