500kV输电线路直升机巡检环境因素对红外测温的影响

通过对500 kV输电线路直升机巡检中红外测温结果进行分析,将影响红外测温的环境因素分为辐射率、环境温度、相对湿度和测量距离4种,分别对其影响程度和影响方式进行分析。分析认为,在4种因素中相对湿度和测量距离对于直升机巡检测温的影响较小,对测温影响较大的是辐射率和环境温度。其中较低辐射率的目标物体在测温过程中会产生明显的环境反射现象,严重影响测温结果,甚至会产生故障点误判的情况。针对环境反射现象的形成原理,提出了通过动态视角观察和避开在清晨、霜降天气飞行的方法来识别和减少环境反射现象,为提高机载红外测温结果的准确性提供借鉴。     

Spectral Remote Sensing of Temperature Distribution in Glass

A numerical method is developed for recovering the temperature distribution in glass from spectral radiation emission data. The desired temperature distribution is obtained using an optimization scheme that determines the best temperature profile from the data in a form of discrete points or Legendre polynomials. In order to evaluate the accuracy and validity of the spectral remote sensing method, the recovered temperatures are compared with independent measurements in two different experiments, one of which uses a Mach-Zehnder interferometer. Experimental results are reported for Corning Code 7940 fused silica using a Perkin-Eimer spectrometer to measure the spectral radiant energy emerging from the glass. The recovered and interferometrically measured temperatures are found to be in good agreement, i.e., within about 1 ? percent at temperatures up to about 800 K.     

锅炉过热器炉内壁面温度红外测量信号的波动特征及数据处理方法

电站锅炉系统中,过热器管壁温度是非常重要的监测参数,关系到机组的安全及高效运行。该文模拟电站锅炉内过热器管壁测温条件,开展了一维炉实验台内不锈钢平板表面温度辐射法测量研究,对实验结果进行了时域和频域的分析。结果表明,红外温度计测量所得试件表面温度会有一定的波动,具有随机性和周期性的特征。红外温度计所测温度与管壁真实温度有一定的偏差。在实验分析的基础上,提出小波消噪和温度修正相结合的数据处理方法,提高了辐射测温精度,为准确测量锅炉内过热器管壁温度提供了参考。     

Preliminary Investigation of Prebreakdown Phenomena and Chemical Reactions Using a Pulsed High-Voltage Discharge in Water

Prebreakdown phenomena in water were investigated for point-plane geometries using high-voltage pulses. Spot discharges, filamentary magenta streamers, isolated microdischarges, and microbubbles were observed and photographed. Emission spectra were obtained using a prism spectrograph. Maximum streamer lengths were determined as a function of applied voltage, pulsewidth (decay constant), and water conductivity. The bubbling of gas through the underwater discharge resulted in the disintegration of the gas bubbles, and also caused gas-phase discharges to occur near the nozzle electrode. The production of 03, accomplished by bubbling O2 gas through a discharge in deionized water, was investigated using a colorimetric indigo dye test that measured the concentration of 03 in the water. Chemical reactions occurring when 02 or N2 gas was bubbled through a discharge in an anthraquinone dye solution were studied by photometrically measuring the decolorization of the dye.     

一种变电站电气设备温度在线监测新方法

为了实现对电气设备的远程、实时、在线的可见光图像和红外温度监测,设计并开发了具有红外检测与图像监控功能的系统。针对变电站电气设备在线监测的特点,从红外理论出发,构建了系统测温模型,分析了影响测温的一些因素及大气衰减的影响;完成了大气透射率的仿真计算并提出了温度修正算法以提高测温精度。开发了具有RS-485串口和激光瞄准方式的改进型红外测温仪,并将其红外测温功能与图像监控软件有效结合。该系统可以在图像监控画面上选择特定的电气设备对其进行远程红外测温,并将返回的温度值加以存储和分析。系统具有较高的经济效益和工程实际应用价值。     

UHV GIS内部温度场的红外热诊断技术

为有效地分析研究特高压气体绝缘组合电器(UHV GIS)设备的故障,利用红外热诊断技术分析了UHVGIS设备的内部温度场。在阐述了红外热诊断技术的原理和应用的基础上,针对GIS设备建立了相应的物理模型和数学模型,同时提出了以红外测温装置测量到的设备表面温度作为边界条件,求解传热学导热反问题进而诊断设备内部温度场以及高压导线温度的方法。此外借助有限元分析软件检验了数值计算结果。该方法为进一步利用红外诊断技术分析UHV GIS内部故障奠定了基础。     

应用于微波场的温度测量方法的研究进展

在微波加热过程中,由于温度的准确性会直接影响到化学反应速率与制备样品的性能,所以微波场中温度的准确测量具有十分重要的意义。综述了微波场中传统的温度测量方法包括热电偶测温、光纤测温和红外测温方式在微波场中应用时的局限性。鉴于传统测温手段的局限性,一种新型的温度测量方式-有机金属框架材料(MOFs)温度计因具有高度的可调性以及纳米级的MOFs颗粒能够实现微米级甚至亚微米级的温度测量而受到了广泛的关注,对近年来双发射MOFs温度计以及膜式温度计的研究成果进行了分析,并综述了优化MOFs温度计的方法,讨论了微波场测温技术未来的发展方向。     

Ultrabroadband infrared solid-state lasers

Ultrabroadband infrared transition metal ion-doped solid-state lasers have come of age and are increasingly being used in trace gas monitoring, remote sensing, telecommunications, ophthalmology, and neurosurgery. Operating at room temperature, they are stable, versatile, and easy to handle successors to the color center lasers. They are becoming the critical components in optical frequency standards, space-based remote sensing systems, and may soon find application in femtochemistry and attosecond science. The article reviews the principles and basic physics of these types of lasers, which are distinguished by their ability to support the shortest pulses down to single optical cycle durations and the ultimately broad tuning ranges. The paper further reviews the state of the art in the existing diode-pumped sources of broadly tunable continuous wave, and ultrashort pulsed radiation in the infrared, and provides examples of their successful application to supercontinuum generation, trace gas measurements, and ultrasensitive intracavity spectroscopy. Developments in such lasers as Cr:YAG, Cr:ZnSe, Cr:ZnS, as well as the recently proposed mixed Cr:ZnS/sub x/Se/sub 1-x/ laser, are discussed in more detail. These lasers nearly continuously cover the infrared spectral region between 1.3 and 3.1 /spl mu/m. The gain spectra of these lasers perfectly match and extend toward the infrared spectra of such established ultrabroadband lasers, operating at shorter wavelengths between /spl sim/0.7-1.3 /spl mu/m, as Ti:sapphire, Cr:LiSAF/Cr:LiSGaF and Cr:forsterite. This opens up new opportunities for synthesis of single-cycle optical pulses and frequency combs in the infrared.     

The Measurement of SO2 Concentration in Flue Gases Using Ionization Techniques

The recent concern with the problem of SO2 removal from flue gases has indicated that a need exists for some type of inexpensive yet reasonably accurate instrument to be used as a stack monitor for coal-fired power stations. This paper describes work that was carried out to demonstrate the feasibility of such an instrument based upon the fact that SO2 gas has a very strong affinity for free electrons. This property enables the SO2 concentration to be related to the current flowing in a specially designed ionization chamber that may use either a corona or a radioactive emitter as the ionization source. When used in a differential mode, it is possible to separate interfering effects caused by the broad range of variables encountered in flue gas, such as temperature, gas composition, fly ash, etc. Results are presented showing that excellent sensitivity is obtained in the crucial concentration range of < 1500 parts per million (ppm) SO2 and that the resulting instrument should be ideally suited to direct monitoring of flue gases.     

基于压缩感知与分段 Hermite 插值的 二维温度场重构方法

在遥感测绘、爆炸场测试和物流安全等领域,往往需要高精度测量二维温度场信息。由于测量面积较大或者监测设备有限,经常导致温度场测试精度和分辨率较低。为此,本文结合压缩感知与分段Hermite插值理论提出一种二维温度场压缩重构方法。该方法首先对温度场进行随机欠采样;然后对采样结果进行分段Hermite插值以提高采样率;最后利用插值结果进行OMP高概率重构。该方法可以有效降低二维温度场测试的测量点数量。试验表明,在压缩率为75%情况下,二维温度场的重建误差不大于6.5%。     

The Sparking Characteristics of Needle-To-Plane Coronas

The sparking voltage (Vs) and maximum presparking corona current (Imax) of needle-to-plane coronas have been measured as independent functions of polarity, tip radius (r), and needle-to-plane spacing (S). For a negative needle, Vs and Imax increase with S but are independent of r. For positive polarity, Vs and Imax increase with both S and r. Thus to increase the corona current while avoiding a spark, one should increase the spacing and voltage. At large spacings, Imax is appreciably greater for negative polarity than for positive. Analysis of the data reveals that for negative polarity the maximum presparking current may be written in the approximate form Imax?Vs(Vs-VO)S-2 where VO is the corona threshold voltage. This is an extrapolation of a relationship previously obtained for Trichel pulse corona. The analysis shows that the transition from negative corona to sparking occurs when the linear space charge density in the gap reaches a critical value Qs/S ?10-10 coul/mm, where Qs is the total space charge in the gap just before sparking occurs. It is shown that this condition amounts to spatial overlap of the multiple ion clouds in the gap, thereby creating a continuous ionized channel between the electrodes.     

Duty Cycle Characteristics for DC Servo Motors

This paper describes methods of calculating the peak temperature rise of the armature winding of a dc servo motor when operated on a specific duty cycle and for torque values greater than rated. It also defines the relationship of the maximum allowable time ON (tR) for a desired output torque such that the peak temperature rise will not exceed the temperature rating of the insulation thus ensuring adequate insulation life. A new approach of specifying these duty cycle characteristics is suggested which can be used to find the maximum time ON (tR) for a given torque as well as the peak temperature rise for any length of time ON (t1). The use of these characteristics can be extended from repetitive cycles to duty cycles where output torque requirements within a cycle are varying. This analytical approach is supported by experimental data.     

光纤温度传感系统在火灾探测中的应用

线型光纤温度传感系统是一种用于实时测量空间温度场分布的传感系统,可对光纤所敷设部位的温度分布进行不间断的监测,遇异常的温度变化则锁定事故部位并立即报警,特别适用于要在大范围内进行多点温度测量的场合.应用这种新型的在线监测传感技术构建的新型感温探测系统,提高了消防自动报警系统的可靠性、灵敏度和精准度.     

On the Nature of Poling by Corona Charging and the Pyroelectric Effect in PVF2

The effect of corona charging (at 12.5 kV) of polyvinylidine fluoride (PVF2) is studied by infrared spectroscopy and X-ray diffraction techniques. The results show that changes in molecular conformation occur with such a poling process that is in agreement with Southgate. The pyroelectric coefficient was observed to increase significantly after such a poling, reaching a maximum value of ~3 nC/cm2K at ~343 K. It is suggested that the pyroelectricity in PVF2 at this temperature is due to dipolar orientation.     

质子交换膜燃料电池表面温度分布的测量

温度分布、电流密度的分布与燃料电池的寿命有密切关系。应用红外热成像技术测量了特殊设计的质子交换膜燃料电池的阴极外表面的温度分布。燃料电池的反应面积为5 cm2。实验中采用了日本NEC公司的型号为TH 5102的热像仪。实验结果表明红外热成像技术能有效地测量质子交换膜燃料电池的外表面温度。电池阴极表面温度分布随电池温度和氧气流量变化而变化。     

红外测温技术在变压器高压套管故障诊断的应用

基于红外测温原理,介绍红外测温技术在电气设备故障诊断中的应用,并结合案例分析一起经红外测温发现的500 kV主变高压套管渗油缺陷。通过红外测温仪检测到套管上下部位出现温度分层现象,得出套管发生内渗而导致缺油缺陷的结论,现场解体检查验证分析结果的正确性和有效性,并针对此案例提出相应的预防性措施。     

A Remote Compact Sensor for the Real-Time Monitoring of Human Heartbeat and Respiration Rate

A remote compact sensor system for the detection of human vital signs (heartbeat and respiration rate) is presented. The frequency band of 24 GHz is employed for remote sensing. For the compact size, the developed sensor uses a circularly polarized electromagnetic wave with a single antenna. The sensor system is composed of radio-frequency circuits, a signal conditioning block, a data-acquisition unit, and a signal-processing part. The peak detection of the power spectral density with a tracking algorithm is utilized for the real-time detection of human vital signs. The measurement result is compared with the commercial fingertip sensor. The comparison result shows excellent agreement.      

A multifunction optoelectronic measurement system for ac three-phase networks

A new measurement system is considered that contains a fiberoptical waveguide that implements galvanic isolation (separation) between measurement and operator areas (zones) serves for transferring (transmitting) measurement information from the measurement area to the operator area, as well as for transferring optical radiation in the measurement area. The energy of this optical radiation is converted to the electrical energy to supply (power) at the circuit of the remote module (unit). In contrast to known hybrid measurement systems for measuring the current strength, this system enables the measurement of a number of the parameters, namely, the current, frequency, phase, and temperature of a current-carrying wire.     

Multipole Corrections to Dielectrophoretic Force

Calculation of the dielectrophoretic (DEP) force on a neutral dielectric partide in a nonuniform electric field is simplified by using the effective dipole method. Once the instantaneous effective dipole moment peff(t) has been correctly identified using Gauss's law, then the expression (peff(t)?)E0(t) is used to determine the force on the particle. Recent work has demonstrated that the effective dipole method produces a result consistent with integration of the Maxwell stress tensor. In the present paper, the issues concerning identification of peff(t) are aired, and an alternate derivation of the DEP force on a conducting dielectric sphere immersed in a conducting dielectric fluid is offered. Then the effective dipole theory is generalized to account for higher order (multipole) contributions. This new effective multipole theory is restricted to spherical particles in a cylindrically symmetric cusped electric field, but the analysis leads to straightforward computation of the quadrupolar correction factor for the DEP force. A quantitative example is provided.     

多孔陶瓷燃烧器火焰温度的测定

实验采用红外辐射测温法测出了多孔陶瓷燃烧器中预混火焰沿气流方向的温度分布曲线。结果表明，燃烧器中的燃烧火焰与自由火焰相比，燃烧温度显著提高，验证了理论预测的这一特性；也说明利用红外测温能克服热电偶等直接测温的缺点，得到了温度变化的真实特性。图５参８