Local Measurement of Gas-Liquid Bubbly Flow with a Double-Sensor Probe

A double-sensor probe was used to measure local interfacial parameters of a gas-liquid bubbly flow in a horizontal tube. The parameters included void fraction, interfacial concentration, bubble size distribution, bubble frequency and bubble interface velocity. The authors paid special attention to the probe design and construction for minimizing measurement errors. Measures were also taken in the design of sensor ends for preventing corrosions in the flow. This is an effort to improve the current double-sensor probe technique to meet the ever-increasing needs to local parameter measurements in gas-liquid two-phase flows.

Comparative study of electrostatic sensors with circular and probe electrodes for velocity measurement of pulverised coal

This paper presents recent progress on the velocity measurement of pulverised coal in pneumatic pipelines using electrostatic sensors in combination with correlation signal processing techniques.A comparative study of electrostatic sensors with circular and probe electrodes was conducted on a 94 mm bore horizontal pipeline in a 4 MW furnace.The advantages and limitations of both sensors are discussed.Experimental results demonstrate that both sensors are capable of providing pulverised coal velocity measurement with excellent repeatability and dynamic response.

3D printed fiber-optic nanomechanical bioprobe

Ultrasensitive nanomechanical instruments,e.g.atomic force microscopy(AFM),can be used to perform delicate biomechanical measurements and reveal the complex mechanical environment of biological processes.However,these instruments are limited because of their size and complex feedback system.In this study,we demonstrate a miniature fiber optical nanomechanical probe(FONP)that can be used to detect the mechanical properties of single cells and in vivo tissue measurements.A FONP that can operate in air and in liquids was developed by programming a microcantilever probe on the end face of a single-mode fiber using femtosecond laser two-photon polymerization nanolithography.To realize stiffness matching of the FONP and sample,a strategy of customizing the microcantilever’s spring constant according to the sample was proposed based on structure-correlated mechanics.As a proof-of concept,three FONPs with spring constants varying from 0.421 N m^(−1)to 52.6 N m^(−1)by more than two orders of magnitude were prepared.The highest microforce sensitivity was 54.5 nmμN^(−1)and the detection limit was 2.1 nN.The Young’s modulus of heterogeneous soft materials,such as polydimethylsiloxane,muscle tissue of living mice,onion cells,and MCF-7 cells,were successfully measured,which validating the broad applicability of this method.Our strategy provides a universal protocol for directly programming fiber-optic AFMs.Moreover,this method has no special requirements for the size and shape of living biological samples,which is infeasible when using commercial AFMs.FONP has made substantial progress in realizing basic biological discoveries,which may create new biomedical applications that cannot be realized by current AFMs.

Portable nano probe for micro/nano mechanical scratching and measuring

A nano probe system which can measure precise contact force in mN scale was demonstrated. The nano probe micro parts or optical parts in nanometer range resolution and scratch was originally designed for on-machine measuring applications and one kind of contact type measuring probes was designed for miniaturized or microfactory system. It ideally should be of small size and able to measure surface topography in nanometer scale. A commercial capacitive displacement sensor was proposed. It was a new concept in nano probe systems which can measure the displacement of shaft driven by the variation of surface topography. The nano probe mainly consisted of three parts： a capacitive displacement sensor, a porous type air slide and a contact probe part with various tip radiuses. The porous type air slide assured the shaft slided smoothly with controllable normal force in mN scale and had high positioning accuracy. The probe part which was directly in contact with target surface, can be applied to micro/nanoscale scratching as well as the measurement of sample topography by a simple tip change.

Development of MEMS-based micro capacitive tactile probe

In this paper, a micro capacitive sensor with nanometer resolution is presented for ultra-precision measurement of micro components, which is fabricated by the MEMS （micro electromechanical systems） non-silicon technique. Based on the sensor, a micro capacitive tactile probe is constructed by stylus assembly and packaging design for dimension metrology on micro/nano scale, in which a data acquiring system is developed with AD7747. Some measurements of the micro capacitive tactile probe are performed on a nano positioning and measuring machine （NMM）. The measurement results show good linearity and hysteresis with a range of 11.6 μm and resolution of better than 5 nm. Hence, the micro capacitive tactile probe can be integrated on NMM to realize measurement of micro structures with nanometer accuracy.

Concept for Floating and Submersible Wireless Sensor Network for Water Basin Monitoring

It will show the feasibility of a Wireless Sensor Network (WSN) devoted to monitoring water basin, river, lake, and sea both on the surface and in depth. The swarm of floating probes can be programmed to periodically sink some tens of meters below the surface, collecting data, characterizing water properties and then coming to the surface again. The life span of the probes may be assured by an on-board power supply or through batteries recharged by solar cells. The basic idea of the WSN is reported together with a detailed analysis of the operational constraints, the energy requirements, and the electronic and mechanical discussion.

Hail Sensing Probes: Feasibility Analysis for Probes to Monitor and Study Hail

This work presents the feasibility study regarding the realization of hail sensing probes for remote sensing and study of hail. The probes are designed as artificial hailstones in order to study both the physical properties of the portion of atmosphere where the formation of hail occurs and the modification of atmospheric conditions while the hailstones are falling to the ground. The basic idea is to realize sensors with a similar fluid-dynamic behavior with respect to hailstones;the density, the weight and the size of the probes are determined. Consequently, the specification of the electronic boards, sensors, and material to realize the probes are studied and presented. The hail sensing probes can be dropped by a plane, or potentially a UAV (Unmanned Aircraft Vehicle), which fly above and through the clouds where the hail formation occurs. During their falling to the ground, the sensors installed on the probe measure directly different parameters such as humidity, temperature, pressure, acceleration. All data are sent to a receiver located on the ground. The study of the sampling frequency of each sensor is presented, together with the analysis of the propagation channel, in order to assure a robust communication link between probes and the ground receiver. The energy balance is also computed. The work demonstrates that a set of this kind of disposable sensors can be realized. They can be used for efficient monitoring operations and studies of hail formation dynamics and conditions, thus increasing the set of instruments for the monitoring and remote sensing of hail.

Review of reflective fiber optic sensors for surface topography measurement

Different from the traditional contact surface topography measurement,reflective intensity-modulated fiber optic sensor(RIM-FOS)has the unique advantages of non-contact nondestructive detection.This paper briefly introduces the principle and performance of RIM-FOS for surface topography measurement and compares with several other methods of topography measurement.Based on the review of its development process,this paper summarizes and analyses the hot issues of RIM-FOS in the surface topography measurement,then predicts the future trend for a guidance of the further study.

New Optical Fiber Pressure Sensor with Reflection Capsule

The ratio measurement by means of the sensing optical fiber and the reference fiber with different beginning positions, and the technique to improve the stability of the sensor are first described. Then the ability to restrain and compensate the interference of the same nature through the double channel ratio measurement is illustrated. Finally, the performance of sensor and its engineering design are discussed.

Highly Sensitive Acidic pH Fluorescent Probe Based on A Boradiaza-indacene Derivative

A pH-sensor with a pKa value of 5.05 based on 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene（BODIPY） dye was synthesized and demonstrated to be highly sensitive within a pH range of 4.0--6.0 and was highly photostable, which makes it a potential pH fluorescent probe. The new pH-sensor will find its application in studying acidic organelles in living cells.

早期香蕉枯萎病Foc4双探针核酸纸基检测传感器研制

为实现对早期香蕉枯萎病4号生理小种(fusarium oxysporum f.sp.cubense 4, Foc4)的准确检测,该研究提出一种基于胶体金的双探针纸基传感器。该传感器将2种不同粒径的胶体金分别与检测探针和信号增强探针结合,利用DNA探针代替抗原和抗体,形成双探针体系,通过增加信号增强探针降低检测限。基于目标序列与双探针体系的碱基互补配对形成“金标探针-目标序列-T线探针”复合物并在传感器的测试区被捕获,10 min内形成肉眼可见的目标产物,通过分析测试条带得到光强度峰面积并代入标准曲线中,实现Foc4定量检测。试验结果表明,双探针纸基传感器的检测限达到0.001 nmol/L,是传统纸基传感器的100倍,提高了检测灵敏度;在0.001~1 000.000 nmol/L范围内,Foc4浓度与测试线光强度峰面积呈线性关系;使用高浓度非互补探针进行试验干扰,发现非互补序列对检测效果基本无影响,表明该传感器具有较好的特异性;香蕉叶片Foc4检测的平均回收率为77.6%~102.3%,相对标准偏差为7.4%~7.7%。与传统形态学观察等检测方法相比,该研究提出的双探针核酸纸基检测传感器可以及时、快速、准确地判断早期Foc4的存在,具有良好的推广性和实际应用价值。

基于多个热成像探头传感器的滑环装置碳刷温度监测与分析

文章设计了一款基于多个热成像探头传感器的滑环装置碳刷温度监测系统,该系统利用热成像探头传感器来获取碳刷的温度数据,并通过数据处理和分析,实现对碳刷温度的监测和报警。系统采用热成像视频监测,增加现地显示装置,通过对系统进行设计,实现了历史数据查询、故障预警等多种功能,可更好地保障水利发电的安全运行。

电容式谷物水分传感器探头设计与试验

针对谷物水分传感器安装困难的问题,基于边缘电容效应设计一种同心圆平面电容式水分传感器探头。通过建立仿真模型,分析可行性,并通过试验研究探头结构变化对探头测量灵敏度和测量范围的影响,最终确定探头尺寸结果的最优组合。当电极的极间距与宽度的比值为5、驱动电极的数量为1时,传感器探头的灵敏性和测量范围最优。以小麦为研究对象,试验表明小麦含水率与输出电容值之间存在二次线性回归,并研究温度对输出电容的影响,建立水分检测模型,在温度为-5℃~40℃、含水率为10%~30%内,相关系数R2为0.997,均方根误差RMSE为0.359。所设计的传感器探头可以满足不同时期小麦含水率测量精度需求,为小麦水分检测提供一种新的传感器探头形式及设计方法。

基于COMSOL仿真软件的电涡流传感器教学探索

为了提升课堂教学效果,辅助学生理解电涡流传感器的检测原理及相关抽象概念,采用COMSOL仿真软件,构建了电涡流传感器探头线圈的仿真模型,并采用有限元的分析方法对其进行求解计算。通过对仿真结果的分析,学生可以直观地看到,当涡流线圈激励频率、提离距离、线圈内径、线圈外径和线圈厚度变化时,电涡流传感器的检测灵敏度将随之发生变化,有助于学生对电涡流传感器相关知识的理解和掌握,提高了学生的学习热情和思考深度。

基于大数据聚类的飞行探测器复合跟踪控制系统设计

飞行探测器会受到气象条件、磁场等环境干扰,影响探测器的运动轨迹,进而影响跟踪精度;为实现对飞行探测器运动轨迹的实时跟踪与控制,设计基于大数据聚类的飞行探测器复合跟踪控制系统;在复合框架体系中,设置主控芯片、伺服驱动设备两类应用结构,并联合信标机元件,调节微惯性传感器器件的实时连接状态,完成飞行探测器复合跟踪控制系统的硬件设计;完善大数据聚类算法,根据跟踪路径节点标定结果,定义具体的复合跟踪坐标系,完成对飞行探测器复合跟踪的实时控制建模,结合相关硬件,实现基于大数据聚类的飞行探测器复合跟踪控制系统的设计;实验结果表明,所设计系统在跟踪1号、2号目标的跟踪准确率平均值分别为96.5%、97.0%,对目标跟踪时延的平均值为0.9 ms,可以保证基站主机对飞行探测器运动轨迹的实时控制能力。

朗缪尔探针及其可展机构设计

为实现对空间环境等离子体参数的测量,依据某航天任务要求,设计并制作了一种朗缪尔探针及其可展机构。该朗缪尔探针主要由传感器、电路盒和可展机构组成,具有锁紧模式和展开模式2种工作状态;可展机构由旋转部分和伸展部分组成,利用扭转弹簧和压缩弹簧进行驱动。为提高机构的尺寸稳定性,制作过程对各个筒体进行了时效和高低温定型处理,球形传感器表面采用金镀层以保证耐蚀性和导电性。通过在地面环境下的测试,验证了朗缪尔探针的可行性和正确性,对可展机构的研究具有实际意义。

一种新型比率荧光毛细管pH传感器的制备及性能

实时便捷的pH检测对于环境监测和医学诊断等领域具有重要应用价值。本文通过溶胶-凝胶法制备了一种比率荧光毛细管pH传感器。该传感器以2.8-羟基芘-1,3,6-三磺酸三钠盐(8-hydroxy-pyrene-1,3,6-tri-sulfonate,HPTS)作为pH敏感的荧光探针,利用HPTS与十六烷基三甲基溴化铵(hexadecyl trimethyl ammonium bromide,CTAB)结合形成HPTS-IP离子对,然后将离子对分散于溶胶-凝胶中,并将其固定于毛细管内壁即制得比率荧光毛细管pH传感器。该传感器利用HPTS在双激发带下的发射强度比值实现比率荧光检测,当pH从5.0上升至8.0时,HPTS的荧光强度比率随pH值增加逐渐增强,pKa值为6.95,通过分析HPTS的比率荧光强度变化可间接监测pH波动。该传感器具有较好的pH敏感性、稳定性和可逆性,且可快速、灵活、便捷地进行实际操作,在环境保护和生物医学领域的pH监测分析方面拥有良好的应用前景。

应用于涡流无损检测的柔性磁阻传感器

为了研究平面探头和曲面探头在检测平面缺陷和曲面缺陷方面的差异,本文分别使用刚性印刷电路板和柔性印刷电路板(FPC)设计了刚性探头和柔性探头。实验结果表明,在平面铝板上,刚性探头和柔性探头的信噪比分别为30.2 dB和24.6 dB。在弯曲缺陷中,刚性探头的信噪比最低为14.8 dB,柔性探头的信噪比最低为27.1 dB。综合考虑温度稳定性、信噪比、价格等因素,刚性探头适用于小曲率的平面缺陷检测,柔性探头适用于曲面检测。

电导探针向量信号处理的泡状流参数分析

泡状流广泛存在于化工、石油、电力等工业场合,对其主要参数的测量不仅是工程设计的必须参考,也是进一步开发两相流理论模型的依据。文章提出并制作了小型四电极电导探针测量空气-水盖泡状流,可以获得局部含气率、界面面积浓度和气泡弦长,且通过已知或合理假设的界面运动方向可获得界面的指向和速度,并通过实验对比四电极电导探针和可视化两种测量方法。结果表明:两种方法具有良好的一致性,四电极电导探针简单、高效,可以准确地测量泡状流中相界面指向等参数,还能有效地解决多维两相流参数测量问题。

一种可快速检测大肠杆菌O157:H7的纸基传感器的制备与应用

大肠杆菌O157:H7是一种致病性较强的食源性细菌,通常在生制食品中被检出,一旦被人体摄入会引发肠道疾病,严重危害公众健康。本研究制备了功能化的长余辉探针,并结合适配体的特异性识别功能构建了能快速检测大肠杆菌O157:H7的纸基传感器,检出限达7.5×10^(3) CFU·mL^(-1)。该传感器可同时检测3个样品,具有特异性好、操作简便和环境友好的特点,可应用于大量样品中大肠杆菌O157:H7的快速筛查。