Gas-sensor property of single-molecule device:F_2 adsorbing effect

The single thiolated arylethynylene molecule with 9,10-dihydroanthracene core（denoted as TADHA） possesses pronounced negative differential conductance（NDC） behavior at lower bias regime. The adsorption effects of F2 molecule on the current and NDC behavior of TADHA molecular junctions are studied by applying non-equilibrium Green＇s formalism combined with density functional theory. The numerical results show that the F2 molecule adsorbed on the benzene ring of TADHA molecule near the electrode can dramatically suppresses the current of TADHA molecular junction. When the F2 molecule adsorbed on the conjugated segment of 9,10-dihydroanthracene core of TADHA molecule, an obviously asymmetric effect on the current curves induces the molecular system showing apparent rectifier behavior. However, the current especially the NDC behavior have been significantly enlarged when F2 addition reacted with triple bond of TADHA molecule.

Pressure effects in AlAs/Inx Ga1-xAs/GaAs resonant tunnelling diodes for application in micromachined sensors

This paper reports the current-voltage characteristics of [001]-oriented AlAs/InxGa1-xAs/GaAs resonant tunnelling diodes （RTDs） as a function of uniaxial external stress applied parallel to the [110] and the [1^-10] orientations, and the output characteristics of the GaAs pressure sensor based on the pressure effect on the RTDs. Under [110] stress, the resonance peak voltages of the RTDs shift to more positive voltages. For [1^-10] stress, the peaks shift toward more negative voltages. The resonance peak voltage is linearly dependent on the [110] and [1^-0] stresses and the linear sensitivities are up to 0.69 mV/MPa, -0.69 mV/MPa respectively. For the pressure sensor, the linear sensitivity is up to 0.37 mV/kPa.

Temperature effect on the reference frequency of FDR soil moisture sensor

The FDR automatic soil moisture sensor must determine reference frequency in the air and water. Experimental studies show that the water reference frequency is influenced by water temperature. The variation of the reference frequency of the sensor is measured with the change of the water temperature,then analysis the influence of the volume water content measurement of the sensor,analysis found that the error is not more than 3% for the measurement of the volumetric water content of the temperature.

An Energy-Aware Routing Protocol Based on Effective Transmission in Sensor Networks

In order to minimize the energy consumption in the discovery of the routing path, this paper introduces a novel concept of effective transmission （ET） that ensures each forwarding node is not only farther from the source node, but also nearer to the destination node with respect to its sender, An energ-aware routing protocol based on ET is proposed. It enables the energy consumption for each hop to be the least for the transmission. The simulation results show the routing protocol is effective in the performance of energy consumption comparing with some other routing protocols.

基于磷脂双层的纳米粒子微传感分析系统

大气污染日益严重,悬浮纳米粒子和病毒颗粒通过肺泡进入体内,给人体带来未知的健康危害。本文通过将磷脂双层集成在场效应晶体管延长栅极表面体外模拟局部肺泡膜,设计并搭建了肺泡膜-纳米粒子相互作用实时监测系统。通过对粒子作用下源漏电流尖峰信号的检测与分析,该系统可以获取纳米粒子/病毒颗粒与肺泡膜相互作用行为的精确定量数据。测试结果表明,所提出微传感系统表面磷脂膜具有良好的完整性和生物活性,集成磷脂双层的延长栅极性能稳定、响应快、灵敏度高,可以准确、及时捕获带电离子跨膜转移信号,有望成为膜-粒相互作用行为有效的体外研究平台,推广用于广泛评估纳米粒子对人体健康的影响。

基于煤矸振动特性的放顶煤支架传感器优化布置策略研究

针对放顶煤煤矸智能识别研究,为提供完整且有效的煤矸振动信号采集方案,提出了一种基于煤矸振动特性的放顶煤液压支架尾梁传感器优化布置策略。首先,对尾梁模型进行模态分析,提取振型矩阵,利用有效独立法初选测点;其次,获取尾梁试验台相应初选测点的落煤和落矸振动信号,进行特征提取;然后,对所提取特征进行t分布式随机邻域嵌入(t-distributed Stochastic Neighbor Embedding,t-SNE)降维可视化,筛选出5个对落煤和落矸信号区分敏感的特征,并以此作为目标特征;最后,经核密度估计法估算目标特征的概率密度函数,利用K-L(Kullback-Leibler)散度评估各测点组合信号与完整信号的近似性和煤矸特征的差异性,构建煤矸振动信号评价指标,结合Fisher信息矩阵准则,形成综合评价指标,确定尾梁的传感器布置最优方案。结果表明,该方法在满足模态可观测性的基础上不仅减少了传感器数量,还使得所测振动信号具有更好的煤矸差异性和信息完整性。

Metal–Organic Framework-Based Sensors for Environmental Contaminant Sensing

Increasing demand for timely and accurate environmental pollution monitoring and control requires new sensing techniques with outstanding performance, i.e.,high sensitivity, high selectivity, and reliability. Metal–organic frameworks(MOFs), also known as porous coordination polymers, are a fascinating class of highly ordered crystalline coordination polymers formed by the coordination of metal ions/clusters and organic bridging linkers/ligands. Owing to their unique structures and properties,i.e., high surface area, tailorable pore size, high density of active sites, and high catalytic activity, various MOF-based sensing platforms have been reported for environmental contaminant detection including anions, heavy metal ions,organic compounds, and gases. In this review, recent progress in MOF-based environmental sensors is introduced with a focus on optical, electrochemical, and field-effect transistor sensors. The sensors have shown unique and promising performance in water and gas contaminant sensing. Moreover, by incorporation with other functional materials, MOF-based composites can greatly improve the sensor performance. The current limitations and future directions of MOF-based sensors are also discussed.

The research of optical windows used in aircraft sensor systems

The optical windows used in aircrafts protect their imaging sensors from environmental effects. Considering the imaging performance, flat surfaces are traditionally used in the design of optical windows. For aircrafts operating at high speeds, the optical windows should be relatively aerodynamic, but a flat optical window may introduce unacceptably high drag to the airframes. The linear scanning infrared sensors used in aircrafts with, respectively, a flat window, a spherical window and a toric window in front of the aircraft sensors are designed and compared. Simulation results show that the optical design using a toric surface has the integrated advantages of field of regard, aerodynamic drag, narcissus effect, and imaging performance, so the optical window with a toric surface is demonstrated to be suited for this application.

面向新型电力系统的光纤电流传感技术研究进展

电流传感测量在电力系统的计量、保护、控制等领域有举足轻重的作用。随着中国新型电力系统建设纲要提出并且智能化、数字化水平不断增长,电流传感器面临着宽频带、高动态、小型化的需求。相比于传统电磁互感器,基于法拉第效应、磁致伸缩、磁流体、热效应等原理的先进电流测量技术在宽幅值、宽频带、电磁免疫上各有优势;另一方面,针对新型电力系统的未来场景需求,传感器的部署、精度要求和可靠运行面临重大挑战。从电流测量机制方面,分别介绍了基于法拉第效应、热光效应、磁流体和磁致伸缩效应的电流传感技术。在此基础上,指出电流传感技术在传感方式、频率特性、环境适应性、直流测量等方面的挑战,需要新的传感材料以及拓扑结构提升其测量性能。之后,提出光纤电流测量发展趋势建议,为准确度高、适应性好的光纤电流传感器在新型电力系统建设中的广泛应用提供技术指导。

考虑趋肤效应的磁致伸缩位移传感器输出特性

针对磁致伸缩位移传感器检测精度偏低的问题,文中提出了一种考虑趋肤效应的磁致伸缩位移传感器输出电压计算模型。在阐述磁致伸缩位移传感器工作原理的基础上分析了趋肤深度的影响,并考虑在威德曼效应和压磁效应的作用下进行理论分析。通过激励脉冲信号作用在波导丝上产生的趋肤深度,对激励脉冲电流在不同频率下作用在波导丝时与磁致伸缩位移传感器输出电压的关系进行仿真。采用搭建的实验平台进行验证,得出了激励脉冲电流频率的最佳参数值。仿真实验验证了考虑趋肤效应作用下磁致伸缩位移传感器输出电压模型的正确性,进一步提高了磁致伸缩位移传感器的检测精度并丰富了其数学模型。

X-ray detection based on complementary metal-oxide-semiconductor sensors

Complementary metal-oxide-semiconductor(CMOS) sensors can convert X-rays into detectable signals; therefore, they are powerful tools in X-ray detection applications. Herein, we explore the physics behind X-ray detection performed using CMOS sensors. X-ray measurements were obtained using a simulated positioner based on a CMOS sensor, while the X-ray energy was modified by changing the voltage, current, and radiation time. A monitoring control unit collected video data of the detected X-rays. The video images were framed and filtered to detect the effective pixel points(radiation spots).The histograms of the images prove there is a linear relationship between the pixel points and X-ray energy. The relationships between the image pixel points, voltage, and current were quantified, and the resultant correlations were observed to obey some physical laws.

Analyzing the transient effects of 60Co gamma rays in a CIS by Monte Carlo method

The objective of this work is to analyze the transient effects of ^60Co gamma rays in the CMOS image sensor (CIS) using the Monte Carlo method, based on Geant4. The track, energy spectrum, and angle of produced electrons when gamma rays traversed a silicon or silicon dioxide cube were calculated. A simplified model of a 500 × 500 CIS array was established, and the transient effects of gamma rays in the CIS were simulated. The raw images were captured when the CIS was irradiated by gamma rays. The experimental results were compared with the simulation results. The characteristics of the typical events induced by transient effects were analyzed.

Piezoresistive Characteristic of Conductive Rubber for Flexible Tactile Sensor

In the research of 2D flexible tactile sensor matrix,pressure-sensitive conductive rubber was developed and tested in which carbon black was used as its conductive phase and silicon rubber as its matrix layer.Experiments were undertaken and the resultant data were used for its piezoresistive characteristics investigation for two kinds of electrode connection configurations,the surface directive connection and embedded connection.It is found that due to the rather strong nonlinearity of the piezoresistive characteristic curves obtained,a higher correlation relationship can be obtained by means of quadratic polynomial fitting.It also showed that the embedded electrode assembling has higher fitting accuracy while the surface directive connection has better mechanical sensitivity.

A design and application of compound multi-functional sensor in wood-based panel processing

A compound multi-functional sensor was designed by the study on the on-line testing technology of wood-based panels, and its properties of shape, functions, size, resistance to special environment were studied in details. The operational principles of different sensors, technical flow of manufacturing, development of software systems of special functions, and the assessments of technical specification were also be introduced. This sensor adopted many new technologies, such as the applications of piezoresistant effect and heat sensitive effect can effectively measure the pressure and temperature, digital signal processing technology was used to extract and treat signals, and resist interference, encapsulation technology was used to keep the normal run of sensor under a harsh environment. Thus, the on-line compound multi-functional temperature/pressure sensor can be applied better to supervise the production of wood-based panels. All technical specifications of the compound multi-functional sensor were tested and the results met the requirements of the equipments.

The Sensing Behavior to Volatile Organic Compounds Gas on Polypyrrole Sensor under Humidity Condition

Polypyrrole (PPy) powder was synthesized by chemical polymerization at 0℃under atmospheric condition and its layer was prepared by dip coating method on the alumina substrate with interdigitated electrodes.The influence of relative humidity (RH 0～70%) to PPy sensor was studied.The measuring temperature was fixed at 25℃.Methanol and benzene were used as target gases.Various analytic techniques were examined to observe changes in the properties of PPy sensor.The sensitivity of PPy sensor to water vapor was linearly increased with the increasing humidity.As the relative humidity increase from 0% to 70%,the sensitivities to methanol and benzene vapor were reduced,and reduction ratio of sensitivity was 94%, 92.5% at RH 70%,respectively.

Modeling and Rectification of Rolling Shutter Effect in CMOS Aerial Cameras

Due to the electronic rolling shutter, high-speed Complementary Metal-Oxide Semiconductor( CMOS) aerial cameras are generally subject to geometric distortions,which cannot be perfectly corrected by conventional vision-based algorithms. In this paper we propose a novel approach to address the problem of rolling shutter distortion in aerial imaging. A mathematical model is established by the coordinate transformation method. It can directly calculate the pixel distortion when an aerial camera is imaging at arbitrary gesture angles.Then all pixel distortions form a distortion map over the whole CMOS array and the map is exploited in the image rectification process incorporating reverse projection. The error analysis indicates that within the margin of measuring errors,the final calculation error of our model is less than 1/2 pixel. The experimental results show that our approach yields good rectification performance in a series of images with different distortions. We demonstrate that our method outperforms other vision-based algorithms in terms of the computational complexity,which makes it more suitable for aerial real-time imaging.

Surface effects of adsorption-induced resonance analysis on micro/nanobeams via nonlocal elasticity

The governing differential equation of micro/nanbeams with atom/molecule adsorption is derived in the presence of surface effects using the nonlocal elasticity. The effects of the nonlocal parameter, the adsorption density, and the surface parameter on the resonant frequency of the micro/nanobeams are investigated. It is found that, in ad- dition to the nonlocal parameter and the surface parameter, the bending rigidity and the adsorption-induced mass exhibit different behaviors with the increase in the adsorption density depending on the adatom category and the substrate material.

Rapid Evaluation for Feed-axis Lubrication Condition Based on Soft Sensor

Stribeck effect is regarded as the most important feed-axis friction characteristics. According to the relationship between friction and lubrication,a rapid technology for feed-axis lubrication condition evaluation of computer numerical control( CNC) machine tools based on soft sensor is proposed. To obtain its state information,the static friction force,Coulomb friction force,and viscous coefficient are used as the key parameters of the soft sensor for tread analysis. Then the various amplitude and velocity triangular wave test curve, and a precise nonlinear model identification method are presented. The results of the experiments analysis show that this method is feasible and reliable for evaluating feed-axis lubrication condition,which lays the foundation for on-line condition monitoring and reliability evaluation for feed-axis lubrication of machine tools.

Calibration of the Circuit Measurement for the Glucose Sensor

The extended gate field effect transistor (EGFET)has many advantages such as the fabrication is easy,low cost, easy to operate etc.The EGFET was applied to biosensor in recent years.In this study,the tin oxide (SnO_2)pH sensitive membrane was deposited on ITO glass,when the surface voltage which pH membrane changes,the gate voltage and current channel of MOSFET will change immediately to detect concentration of the glucose sensor.In this study we have devoted to research about the calibration of the circuit measurement for the glucose sensor,and study the calibration system of the drift and hysteresis.

基于光学微环谐振器的甲醛传感器模拟研究

针对在日常生活使用广泛但危害性极大的甲醛溶液,基于光学微环谐振器,设计了一种灵敏度高、动态范围大的折射率传感器,用来检测甲醛溶液浓度。本文利用波导微扰理论,确定了使系统灵敏度最大化的波导核心尺寸,利用有限元进行模拟计算。结果发现:利用该传感器如果检测到10^(-5)的相对波长位移,那么就可以检测到10^(-4)的相对折射率变化,并且通过包层去除方法还可进一步提升该传感器的灵敏度,与其他方法相比,这种甲醛溶液探测传感器的灵敏度有了很大程度的提升,对实际甲醛溶液的测量有着实际指导意义。